[wiki migration] Pages under docs/postmortems/ (#148798)

This moves the wiki pages that have a final destination under docs/postmortems/ as planned in [flutter.dev/go/migrate-flutter-wiki-spreadsheet](https://docs.google.com/spreadsheets/d/1x65189ZBdNiLRygpUYoU08pwvXD4M-Z157c6pm8deGI/edit?usp=sharing) 

It also adds the team labels to the label bot for future PRs.

Changes to the content were only updating cross links, or links to refer to the main branch rather than master.
Remaining links to the wiki will be updated once all other pages have finished moving, they still work in the meantime.

Part of https://github.com/flutter/flutter/issues/145009

.github/labeler.yml

@@ -158,6 +158,11 @@ platform-web:
       - '**/*.expect'
       - '**/*test_fixes*'
 
+team:
+  - changed-files:
+    - any-glob-to-any-file:
+      - docs/postmortems/**/*
+
 team-android:
   - changed-files:
     - any-glob-to-any-file:
@@ -167,6 +172,7 @@ team-ecosystem:
   - changed-files:
     - any-glob-to-any-file:
       - docs/ecosystem/**/*
+
 team-engine:
   - changed-files:
     - any-glob-to-any-file:

docs/postmortems/Postmortem-Beta-1-Release.md

@@ -25,7 +25,7 @@ Description: Flutter launched beta 1 on February 27, 2018.  This document attemp
 | _14:40_ | [@timsneath](https://github.com/timsneath) runs into more trouble upgrading.  [@tvolkert](https://github.com/tvolkert) begins trying to diagnose based on the reports. |
 | _16:53_ | After a few back-and-forths with [@timsneath](https://github.com/timsneath) over email, [@tvolkert](https://github.com/tvolkert) enlists the help of [@jason-simmons](https://github.com/jason-simmons) and [@cbracken](https://github.com/cbracken) in tracking down the cause for the problems [@timsneath](https://github.com/timsneath) is encountering.  The goal is to determine whether the problems are an outlier unique to [@timsneath's](https://github.com/timsneath) setup or whether they’re likely to affect most users once the influx of users begins. |
 | _17:30_ | [@jason-simmons](https://github.com/jason-simmons) discovers that before [#14507](https://github.com/flutter/flutter/pull/14507) (v0.0.24), the “channel” command could create local (non-tracking) branches and that if [@timsneath](https://github.com/timsneath) was bitten by this, it would explain the behavior he’s seeing.  The team tentatively decides the errors that [@timsneath](https://github.com/timsneath) is seeing are likely an outlier. |
-| _20:00_ | [@tvolkert](https://github.com/tvolkert) manages to reconstruct [@timsneath's](https://github.com/timsneath) environment setup and confirms [@jason-simmons'](https://github.com/jason-simmons) theory.  The team adds a [section to the wiki](https://github.com/flutter/flutter/wiki/Flutter-build-release-channels#workaround) covering this case for users who may run into it. |
+| _20:00_ | [@tvolkert](https://github.com/tvolkert) manages to reconstruct [@timsneath's](https://github.com/timsneath) environment setup and confirms [@jason-simmons'](https://github.com/jason-simmons) theory.  The team adds a [section to the wiki](../releases/Flutter-build-release-channels.md#workaround) covering this case for users who may run into it. |
 
 ### _2018/02/27_
 
@@ -58,7 +58,7 @@ Description: Flutter launched beta 1 on February 27, 2018.  This document attemp
 
 * Our internal Google tests purposely don’t exercise our external build code paths (e.g. Gradle builds) — since within Google, everything is built using Bazel.  This meant that although the gallery was unable to be built on the beta branch ([#14912](https://github.com/flutter/flutter/issues/14912)), we had no knowledge of this failure until after beta was pushed (and [@mit-mit](https://github.com/mit-mit) manually discovered the breakage).  The bug had actually already been fixed on a newer dev build (in [#14714](https://github.com/flutter/flutter/pull/14714)), but we didn’t mark the affected build range as bad until after this was discovered and traced back to code that pointed to the existing fix. Our external tests were also [allowing failures on Travis](https://github.com/flutter/flutter/blob/5b46e0a4bef24e1c1302ba3ca40a99bd20a192da/.travis.yml#L18-L19), which was intentional at the time because we didn’t yet have confidence in those tests.  In addition to fixing the issue, [#14714](https://github.com/flutter/flutter/pull/14714) also enabled those tests on Travis.
 
-* The Flutter [release process](https://github.com/flutter/flutter/wiki/Release-process#rolling-the-beta-channel) didn’t call out the need to build and run the gallery as part of the beta vetting process, which further allowed the previous issue to go unnoticed.
+* The Flutter [release process](../releases/Release-process.md#rolling-the-beta-channel) didn’t call out the need to build and run the gallery as part of the beta vetting process, which further allowed the previous issue to go unnoticed.
 
 * The Flutter team didn’t have on its radar to mark builds as bad when they saw or fixed issues that would warrant marking a build as bad.  It’d be nice to have a better (ideally more automated) process around this.
 
@@ -78,7 +78,7 @@ Description: Flutter launched beta 1 on February 27, 2018.  This document attemp
 
 ### Bugs That Got in the Way
 
-* In the “channel” command, we weren’t fetching updated refs from GitHub before [checking out the branch](https://github.com/flutter/flutter/blob/eaa9b47a4ac278a9439468911d2c361a472b114b/packages/flutter_tools/lib/src/commands/channel.dart#L103).  This meant that if a user had switched to the beta branch in the past, then switched back to the alpha/dev branch as their primary channel, their beta Git head would be pointing to a commit in December.  Net result: we had to [recommend](https://github.com/flutter/flutter/wiki/Flutter-build-release-channels#how-to-change-channels) that users run `flutter channel beta && flutter upgrade`, which is clunky.
+* In the “channel” command, we weren’t fetching updated refs from GitHub before [checking out the branch](https://github.com/flutter/flutter/blob/eaa9b47a4ac278a9439468911d2c361a472b114b/packages/flutter_tools/lib/src/commands/channel.dart#L103).  This meant that if a user had switched to the beta branch in the past, then switched back to the alpha/dev branch as their primary channel, their beta Git head would be pointing to a commit in December.  Net result: we had to [recommend](../releases/Flutter-build-release-channels.md#how-to-change-channels) that users run `flutter channel beta && flutter upgrade`, which is clunky.
 
 * Until Feb 7 ([#14507](https://github.com/flutter/flutter/pull/14507)), we had a bug in the channel switching logic that would create branches as local (non-tracking) branches.  If users tried to upgrade such channels, they’d get an error message about “no upstream repository configured.”  Users who had tried switching to the beta channel that we had quietly pushed in December 2017 were bitten by this and found their local Git repository in a bad state.  This likely only affected a very small number of users (perhaps only members of the Flutter team), but [@timsneath](https://github.com/timsneath) was one such user, and it took some time to remotely diagnose what was going on with his setup and whether his problems were indicative of a larger issue that was going to affect a large subset of our users.  This time added uncertainty to our launch during crunch-time, where we weren’t sure if we should call off the launch announcements.
 
@@ -107,12 +107,12 @@ Description: Flutter launched beta 1 on February 27, 2018.  This document attemp
 
 | Action Item | Owner | Issue | Notes |
 |-------------|-------|-------|-------|
-| Add a wiki page on identifying bad builds | [@tvolkert](https://github.com/tvolkert) |        | [Done](https://github.com/flutter/flutter/wiki/Bad-Build-Identification) |
+| Add a wiki page on identifying bad builds | [@tvolkert](https://github.com/tvolkert) |        | [Done](../releases/Bad-Builds.md) |
 | Send an email to the core Flutter team about the need to think about marking builds as bad. | [@tvolkert](https://github.com/tvolkert) || Done |
-| Update our release process to call out the need to ensure that the gallery can be built and run. | [@tvolkert](https://github.com/tvolkert) || [Done](https://github.com/flutter/flutter/wiki/Release-process#rolling-the-beta-channel) |
-| Update release process to require that the Travis build go green on the beta branch before sending out any announcements or issuing any public communications. | [@tvolkert](https://github.com/tvolkert) || [Done](https://github.com/flutter/flutter/wiki/Release-process#rolling-the-beta-channel) |
-| Make a beta pusher group in GitHub, to control who has access to push beta releases. | [@Hixie](https://github.com/Hixie) || [Done](https://github.com/flutter/flutter/wiki/Release-process#rolling-the-beta-channel) |
-| Update beta release process to require that the candidate dev build “can be successfully upgraded to from the dev build to which the beta branch currently points.” | [@tvolkert](https://github.com/tvolkert) || [Done](https://github.com/flutter/flutter/wiki/Release-process#rolling-the-beta-channel) |
+| Update our release process to call out the need to ensure that the gallery can be built and run. | [@tvolkert](https://github.com/tvolkert) || [Done](../releases/Release-process.md#rolling-the-beta-channel) |
+| Update release process to require that the Travis build go green on the beta branch before sending out any announcements or issuing any public communications. | [@tvolkert](https://github.com/tvolkert) || [Done](../releases/Release-process.md#rolling-the-beta-channel) |
+| Make a beta pusher group in GitHub, to control who has access to push beta releases. | [@Hixie](https://github.com/Hixie) || [Done](../releases/Release-process.md#rolling-the-beta-channel) |
+| Update beta release process to require that the candidate dev build “can be successfully upgraded to from the dev build to which the beta branch currently points.” | [@tvolkert](https://github.com/tvolkert) || [Done](../releases/Release-process.md#rolling-the-beta-channel) |
 | Update the release process to include downloading and installing the packaged archive for the dev build that represents the prior beta — and ensuring that it’s able to upgrade to the newest release. | [@gspen...](https://github.com/gspencergoog) |||
 
 ### Fixes

docs/postmortems/Postmortem-Widespread-Gradle-failures-on-Flutter-v1.12.13-hotfix.5.md

@@ -1,5 +1,3 @@
-This document is published in our wiki on: https://github.com/flutter/flutter/wiki/Postmortem:-Widespread-Gradle-failures-on-Flutter-v1.12.13-hotfix.5
-
 # Flutter postmortem: Widespread Gradle failures on Flutter v1.12.13+hotfix.5
 
 Status: final<br>
@@ -19,7 +17,7 @@ User impact: Users of the following plugins: url_launcher, google_sign_in, video
 stuartmorgan@ notices that Flutter applications that are using non-Android plugins are failing to build for Android (same for iOS) and files https://github.com/flutter/flutter/issues/39657. The root cause is that the Flutter gradle plugin assumes that all plugins include an Android implementation and tries to build it.
 
 ### 2019-09-16
-stuargmorgan@ prototypes [a fix](https://github.com/flutter/flutter/compare/master...stuartmorgan:wip-platform-plugin-files?expand=1). That fix requires migration of existing plugins.
+stuargmorgan@ prototypes [a fix](https://github.com/flutter/flutter/compare/main...stuartmorgan:wip-platform-plugin-files?expand=1). That fix requires migration of existing plugins.
 
 ### 2019-09-18
 As a temporary workaround for the issue above (Android only), amirh@ lands https://github.com/flutter/flutter/pull/40640 which makes `flutter.gradle` skip packages that do not have an `android/build.gradle` file, this workaround lives in the Flutter SDK and does not require plugin migration.

docs/postmortems/README.md

@@ -0,0 +1,19 @@
+This page lists incidents for which we have written retrospectives and postmortems.
+
+## Postmortems
+
+When adding a new incident, start from the [postmortem template](postmortem-template.md).
+
+* [Postmortem: Build Breakage on 2016-11-08](Postmortem-Build-Breakage-on-2016-11-08.md)
+* [Postmortem: Beta 1 Release](Postmortem-Beta-1-Release.md)
+* [Postmortem: AndroidX plugin migration](Postmortem-AndroidX-plugin-migration.md)
+* [Postmortem: Widespread Gradle failures on Flutter v1.12.13 hotfix.5](Postmortem-Widespread-Gradle-failures-on-Flutter-v1.12.13-hotfix.5.md)
+* [Postmortem: Flutter/Dart Incorrect Version July 2020](https://docs.google.com/document/d/1TeCpj-T0HAp7DcY2ag-q5iX218TeOHNcW5fUusaum0c/edit)
+* [Postmortem: Flutter Gold Summer 2020 Outages](https://docs.google.com/document/d/1cZi84iWFJa9l7TIhSZEnhZlg7bBBIoJLjzx-uLUSLzI/edit?usp=sharing)
+* [Postmortem: Pub.dev outage 2021-03-24](https://docs.google.com/document/d/1hBVi6_1FXoY1hG9zgKFUkqreP7UsnaF4EGspIJh0E2g/edit?hl=en)
+* [Postmortem: Windows Defender alert on 2023-03-26](Postmortem-Windows-Defender-alert-on-2023-03-26.md)
+* [Postmortem: flutter.dev outage on August 26 2023](Postmortem-flutter.dev-outage-on-August-26-2023.md)
+
+## Retrospectives
+
+* [Retrospective: Flutter 2.8 Stable Release](Retrospective-Flutter-2.8-Stable-Release.md)  16 December 2021

docs/postmortems/Retrospective-Flutter-2.8-Stable-Release.md

@@ -64,7 +64,7 @@ Xcode/Mac/iOS were force updated in between the beta to stable time window
     * ~6 days
 * Create a solid release playbook on the wiki to be followed.
   * Should be clear enough that two interns (meaning, two inexperienced people new to the team who have the appropriate permissions) should be able to make a release without supervision while everyone else is on vacation. (It has to be two because you need two people to authorize a release).
-  * https://github.com/flutter/flutter/wiki/Release-process should be (or point to) that process doc; other pages on the wiki should be up to date also.
+  * [Release Process](../releases/Release-process.md) should be (or point to) that process doc; other pages on the wiki should be up to date also.
 * Align beta and stable release processes.
 * Practice release dry runs.
   * Have people who have never followed the steps before practice the steps, to find where the documentation is missing important details.

docs/unsorted_wiki/Postmortems-and-Retrospectives.md

@@ -1,19 +0,0 @@
-This page lists incidents for which we have written retrospectives and postmortems.
-
-## Postmortems
-
-When adding a new incident, start from the [[postmortem template]].
-
-* [[Postmortem: Build Breakage on 2016-11-08]]
-* [[Postmortem: Beta 1 Release]]
-* [[Postmortem: AndroidX plugin migration]]
-* [[Postmortem: Widespread Gradle failures on Flutter v1.12.13 hotfix.5]]
-* [Postmortem: Flutter/Dart Incorrect Version July 2020](https://docs.google.com/document/d/1TeCpj-T0HAp7DcY2ag-q5iX218TeOHNcW5fUusaum0c/edit)
-* [Postmortem: Flutter Gold Summer 2020 Outages](https://docs.google.com/document/d/1cZi84iWFJa9l7TIhSZEnhZlg7bBBIoJLjzx-uLUSLzI/edit?usp=sharing)
-* [Postmortem: Pub.dev outage 2021-03-24](https://docs.google.com/document/d/1hBVi6_1FXoY1hG9zgKFUkqreP7UsnaF4EGspIJh0E2g/edit?hl=en)
-* [[Postmortem: Windows Defender alert on 2023-03-26]]
-* [[Postmortem: flutter.dev outage on August 26 2023]]
-
-## Retrospectives
-
-* [[Retrospective: Flutter 2.8 Stable Release]]  16 December 2021