Add migration guide for Material 3

firebase.json

@@ -123,6 +123,7 @@
       { "source": "/ios-14", "destination": "/platform-integration/ios/ios-debugging", "type": 301 },
       { "source": "/ios-project-migration", "destination": "/platform-integration/ios", "type": 301 },
       { "source": "/layout", "destination": "/ui/layout", "type": 301 },
+      { "source": "/material-3-migration", "destination": "/release/breaking-changes/material-3-migration", "type": 301 },
       { "source": "/packages-and-plugins/androidx-compatibility", "destination": "/platform-integration/android/androidx-migration", "type": 301 },
       { "source": "/packages-and-plugins/c-interop", "destination": "/platform-integration/android/c-interop", "type": 301 },
       { "source": "/packages-and-plugins/plugins-in-tests", "destination": "/testing/plugins-in-tests", "type": 301 },

src/_data/catalog/index.json

@@ -8,7 +8,7 @@
   {
     "name": "Material components",
     "description": "Visual, behavioral, and motion-rich widgets implementing the <a href=\"https://m3.material.io/get-started\">Material 3</a> design specification.<br /><br />Material 3 is the default Flutter interface as of Flutter 3.16. To learn more about this transition, check out <a href=\"https://m3.material.io/develop/flutter\">Flutter support for Material 3</a>.",
-    "pagecontent": "Eventually, Material 2 will be deprecated, but in the short term, you can opt out of Material 3 by setting the <a href=\"https://api.flutter.dev/flutter/material/ThemeData/useMaterial3.html\"><code>useMaterial3</code></a> flag to <code>false</code> in your theme.<br /><br />To catch these widgets in action, check out our live Material 3 <a href=\"https://flutter.github.io/samples/web/material_3_demo\" target=\"_blank\" rel=\"noopener noreferrer\">demo app</a>.<br /><br />You can still check out our legacy <a href=\"/ui/widgets/material2\">Material 2 widgets</a> over at their catalog page.",
+    "pagecontent": "Eventually, Material 2 will be deprecated, but in the short term, you can opt out of Material 3 by setting the <a href=\"https://api.flutter.dev/flutter/material/ThemeData/useMaterial3.html\"><code>useMaterial3</code></a> flag to <code>false</code> in your theme.<br /><br />To migrate your widgets to Material 3, check out the <a href=\"/release/breaking-changes/material-3-migration\">migration guide.</a><br /><br />To catch these widgets in action, check out our live Material 3 <a href=\"https://flutter.github.io/samples/web/material_3_demo\" target=\"_blank\" rel=\"noopener noreferrer\">demo app</a>.<br /><br />You can still check out our legacy <a href=\"/ui/widgets/material2\">Material 2 widgets</a> over at their catalog page.",
     "subcategories": [
       {
         "name": "Actions",

src/_data/sidenav.yml

@@ -151,6 +151,8 @@
       permalink: /cookbook/design/themes
     - title: Material design
       permalink: /ui/design/material
+    - title: Migrate to Material 3
+      permalink: /release/breaking-changes/material-3-migration
     - title: Text
       permalink: /ui/design/text
       children:

src/release/breaking-changes/index.md

@@ -51,6 +51,7 @@ release, and listed in alphabetical order:
 
 ### Released in Flutter 3.16
 
+* [Migrating to Material 3][]
 * [Migrate ShortcutActivator and ShortcutManager to KeyEvent system][]
 * [The `ThemeData.useMaterial3` property is now set to true by default][]
 * [Deprecated API removed after v3.13][]
@@ -64,6 +65,7 @@ release, and listed in alphabetical order:
 * [Windows: External windows should notify Flutter engine of lifecycle changes][]
 * [Windows build path changed to add the target architecture][]
 
+[Migrating to Material 3]: {{site.url}}/release/breaking-changes/material-3-migration
 [Migrate ShortcutActivator and ShortcutManager to KeyEvent system]: {{site.url}}/release/breaking-changes/shortcut-key-event-migration
 [The `ThemeData.useMaterial3` property is now set to true by default]: {{site.url}}/release/breaking-changes/material-3-default
 [Deprecated API removed after v3.13]: {{site.url}}/release/breaking-changes/3-13-deprecations