Update list of codelabs (#2263)

## Pre-launch Checklist

- [x] I read the [Effective Dart: Style] _recently_, and have followed
its advice.
- [x] I signed the [CLA].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Effective Dart: Style]:
https://dart.dev/guides/language/effective-dart/style
[CLA]: https://cla.developers.google.com/
[Discord]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md

README.md

@@ -7,10 +7,14 @@ Here is a list of the codelabs represented here:
 
   - [Adaptive Apps in Flutter](https://codelabs.developers.google.com/codelabs/flutter-adaptive-app) is in [`adaptive_app`](adaptive_app)
   - [Add a user authentication flow to a Flutter app using FirebaseUI](https://firebase.google.com/codelabs/firebase-auth-in-flutter-apps) is in [`firebase-auth-flutterfire-ui`](firebase-auth-flutterfire-ui)
+  - [Add sound and music to your Flutter game](https://codelabs.developers.google.com/codelabs/flutter-codelab-soloud) is in [`audio_soloud`](audio_soloud)
   - [Adding a Home Screen widget to your Flutter App](https://codelabs.developers.google.com/flutter-home-screen-widgets) is in [`homescreen_codelab`](homescreen_codelab)
   - [Adding Google Maps to a Flutter app](https://codelabs.developers.google.com/codelabs/google-maps-in-flutter) is in [`google-maps-in-flutter`](google-maps-in-flutter)
   - [Adding in-app purchases to your Flutter app](https://codelabs.developers.google.com/codelabs/flutter-in-app-purchases) is in [`in_app_purchases`](in_app_purchases)
   - [Adding WebView to your Flutter app](https://codelabs.developers.google.com/codelabs/flutter-webview) is in [`webview_flutter`](webview_flutter)
+  - [Animations in Flutter](https://codelabs.developers.google.com/advanced-flutter-animations) is in [`animations`](animations)
+  - [Build a 2D physics game with Flutter and Flame](https://codelabs.developers.google.com/codelabs/flutter-flame-forge2d) is in [`forge2d_game`](forge2d_game)
+  - [Build a word puzzle with Flutter](https://codelabs.developers.google.com/codelabs/flutter-word-puzzle) is in [`generate_crossword`](generate_crossword)
   - [Building a board game with TensorFlow Agents and Flutter](https://codelabs.developers.google.com/tfagents-flutter) is in [`tfagents-flutter`](tfagents-flutter)
   - [Building a full-stack movie recommendation system](https://codelabs.developers.google.com/tfrecommenders-flutter) is in [`tfrs-flutter`](tfrs-flutter)
   - [Building an animated responsive app layout with Material 3](https://codelabs.developers.google.com/codelabs/flutter-animated-responsive-layout) is in [`animated-responsive-layout`](animated-responsive-layout)