[wiki migration] Remaining pages under docs/about/ (flutter#148782)

This moves the wiki pages that have a final destination under docs/about/ 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 flutter#145009

Author: Piinks

.github/labeler.yml

@@ -118,6 +118,7 @@ framework:
       - packages/flutter_test/**/*
       - packages/integration_test/**/*
       - examples/api/**/*
+      - docs/about/**/*
       - docs/contributing/**/*
       - docs/libraries/**/*
 
@@ -161,6 +162,7 @@ platform-web:
 team:
   - changed-files:
     - any-glob-to-any-file:
+      - docs/about/**/*
       - docs/postmortems/**/*
 
 team-android:

docs/unsorted_wiki/Flutter's-repository-architecture.md renamed to docs/about/Flutter's-repository-architecture.md

@@ -26,7 +26,7 @@ Here are some terms that we use in the Flutter project and what they mean:
 
 - **Modular application delivery**. The ability to package a single app into multiple separate archives when compiling it, and download them independently as needed.
 
-- **NTE**. "Needs-Tests Exemption". Indicates that a PR does not need tests, typically because the PR is refactoring code without changing the semantics of the code, or because it actually does have tests but the automated systems didn't recognize them. A test exemption consists of a comment on the PR that has a line that starts with the string `test-exempt: ` followed by an explanation of why, from someone who is allowed to give test exemptions. A bot will add a comment to a PR if a test exemption is required. See [[Tree Hygiene]] for instructions on getting test exemptions.
+- **NTE**. "Needs-Tests Exemption". Indicates that a PR does not need tests, typically because the PR is refactoring code without changing the semantics of the code, or because it actually does have tests but the automated systems didn't recognize them. A test exemption consists of a comment on the PR that has a line that starts with the string `test-exempt: ` followed by an explanation of why, from someone who is allowed to give test exemptions. A bot will add a comment to a PR if a test exemption is required. See [Tree Hygiene](https://github.com/flutter/flutter/wiki/Tree-hygiene) for instructions on getting test exemptions.
 
 - **Out-of-band (OOB) failure**. A test failure in our CI that is caused by some change external to the repository, not the failing commit (or flake). For instance, an infrastructure change or a change to an external server used by tests could cause an out-of-band failure. In general, CI should minimize the possibility of out-of-band failures by being as hermetic as possible.
 

docs/unsorted_wiki/Glossary.md renamed to docs/about/Glossary.md

@@ -2,15 +2,15 @@ The Flutter project has many teams, including, but not limited to:
 
 * Design languages, covering:
 
-  * The material library ([flutter/flutter packages/flutter/lib/src/material](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/material); label ["f: material design"](https://github.com/flutter/flutter/labels/f%3A%20material%20design))
+  * The material library ([flutter/flutter packages/flutter/lib/src/material](https://github.com/flutter/flutter/blob/main/packages/flutter/lib/src/material); label ["f: material design"](https://github.com/flutter/flutter/labels/f%3A%20material%20design))
 
-  * The cupertino library ([flutter/flutter packages/flutter/lib/src/cupertino](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/cupertino); label ["f: cupertino"](https://github.com/flutter/flutter/labels/f%3A%20cupertino))
+  * The cupertino library ([flutter/flutter packages/flutter/lib/src/cupertino](https://github.com/flutter/flutter/blob/main/packages/flutter/lib/src/cupertino); label ["f: cupertino"](https://github.com/flutter/flutter/labels/f%3A%20cupertino))
 
-* The Flutter framework (code in [flutter/flutter packages/flutter/lib/src/widgets](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/widgets),  [...rendering/](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/rendering),  [...painting/](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/painting), etc; label ["framework"](https://github.com/flutter/flutter/labels/framework))
+* The Flutter framework (code in [flutter/flutter packages/flutter/lib/src/widgets](https://github.com/flutter/flutter/blob/main/packages/flutter/lib/src/widgets),  [...rendering/](https://github.com/flutter/flutter/blob/main/packages/flutter/lib/src/rendering),  [...painting/](https://github.com/flutter/flutter/blob/main/packages/flutter/lib/src/painting), etc; label ["framework"](https://github.com/flutter/flutter/labels/framework))
 
-* The Flutter command line tool ([flutter/flutter packages/flutter_tools](https://github.com/flutter/flutter/blob/master/packages/flutter_tools/), label ["tool"](https://github.com/flutter/flutter/labels/tool))
+* The Flutter command line tool ([flutter/flutter packages/flutter_tools](https://github.com/flutter/flutter/blob/main/packages/flutter_tools/), label ["tool"](https://github.com/flutter/flutter/labels/tool))
 
-* Ecosystem ([flutter/plugins](https://github.com/flutter/plugins), [flutter/packages](https://github.com/flutter/packages), [the plugin infrastructure in flutter/flutter](https://github.com/flutter/flutter/tree/master/packages/flutter/lib/src/services); labels ["plugins"](https://github.com/flutter/flutter/labels/plugins), and ["packages"](https://github.com/flutter/flutter/labels/packages))
+* Ecosystem ([flutter/plugins](https://github.com/flutter/plugins), [flutter/packages](https://github.com/flutter/packages), [the plugin infrastructure in flutter/flutter](https://github.com/flutter/flutter/tree/main/packages/flutter/lib/src/services); labels ["plugins"](https://github.com/flutter/flutter/labels/plugins), and ["packages"](https://github.com/flutter/flutter/labels/packages))
 
 * The Engine ([flutter/engine](https://github.com/flutter/engine) and [flutter/buildroot](https://github.com/flutter/buildroot/); label ["engine"](https://github.com/flutter/flutter/labels/engine))
 
@@ -26,7 +26,7 @@ The Flutter project has many teams, including, but not limited to:
 
 * Developer Relations (e.g. [the samples repo](https://github.com/flutter/samples/), [docs.flutter.dev](https://docs.flutter.dev/))
 
-* Infrastructure (mainly [flutter/cocoon](https://github.com/flutter/cocoon) and [flutter/flutter dev/devicelab](https://github.com/flutter/flutter/tree/master/dev), label ["team: infra"](https://github.com/flutter/flutter/labels/team%3A%20infra))
+* Infrastructure (mainly [flutter/cocoon](https://github.com/flutter/cocoon) and [flutter/flutter dev/devicelab](https://github.com/flutter/flutter/tree/main/dev), label ["team: infra"](https://github.com/flutter/flutter/labels/team%3A%20infra))
 
 There are also specific cross-cutting areas of work that may have their own subteam and that affect multiple subteams (e.g. accessibility, performance, etc).
 
@@ -37,7 +37,7 @@ We also work closely with other projects, such as [Dart](https://dart.dev) and [
 Subteams are responsible for reviewing PRs in their area, triaging issues, and scheduling work.
 How subteams organize themselves is not defined by this document. This document does not attempt to impose a process, merely a set of responsibilities.
 
-See the [[Roadmap]] and [[What should I work on?]] pages for details on how to prioritize work.
+See the [Roadmap](https://github.com/flutter/flutter/wiki/Roadmap) and [What should I work on?](https://github.com/flutter/flutter/wiki/What-should-I-work-on%3F) pages for details on how to prioritize work.
 
 ### Reviewing PRs
 

docs/unsorted_wiki/Project-teams.md renamed to docs/about/Project-teams.md

@@ -45,7 +45,7 @@ We may sometimes gate features behind flags until we are confident of their qual
 
 ## 🤣‬ Have fun doing it
 
-Last, but definitely not least, we want to make sure that our work environment is pleasant for everyone involved. Your health and the health of your family and friends is more important than Flutter. Our community [is welcoming](https://github.com/flutter/flutter/blob/master/CODE_OF_CONDUCT.md). We don't know everything; all of us can make mistakes.
+Last, but definitely not least, we want to make sure that our work environment is pleasant for everyone involved. Your health and the health of your family and friends is more important than Flutter. Our community [is welcoming](https://github.com/flutter/flutter/blob/main/CODE_OF_CONDUCT.md). We don't know everything; all of us can make mistakes.
 
 We want team members to feel empowered to make changes to the code and to our processes.
 
@@ -89,7 +89,7 @@ For each area, we consider the level to which we provide support:
 
 _See also:_
 
-* [Code of Conduct](https://github.com/flutter/flutter/blob/master/CODE_OF_CONDUCT.md)
-* [Contributor Guide](https://github.com/flutter/flutter/blob/master/CONTRIBUTING.md)
+* [Code of Conduct](https://github.com/flutter/flutter/blob/main/CODE_OF_CONDUCT.md)
+* [Contributor Guide](https://github.com/flutter/flutter/blob/main/CONTRIBUTING.md)
 * [Flutter's Culture of Inclusivity](https://flutter.dev/culture)
 * [Flutter culture and how to preserve it](https://medium.com/flutter/flutter-culture-and-how-to-preserve-it-436b4ed1031d)