Docs: migrating from library X

**Is your feature request related to a problem? Please describe.**
Currently, migrating from another library requires you to do a manual comparison of samples from both libraries to fill in the gaps. It would be nice to have documentation for people migrating from other popular state management solutions, such as ChangeNotifier, StateNotifier, MobX, or Redux.

**Describe the solution you'd like**
Identify a few state management libraries that are good candidates for migration documentation. Documentation should mirror Flutter's for migrating from X (React Native, Android, etc.)

**Describe alternatives you've considered**
The current alternative is for people to do the mental translation themselves rather than having ready documentation to review.

**Additional context**
Flutter migration examples:

https://flutter.dev/docs/get-started/flutter-for/react-native-devs
https://flutter.dev/docs/get-started/flutter-for/android-devs