update docs

Author: sachaarbonel

Diff for: packages/stream_feed_flutter/lib/src/widgets/buttons/follow.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:stream_feed_flutter_core/stream_feed_flutter_core.dart';
 
+/// A button to follow or unfollow a user
 class FollowButton extends StatefulWidget {
   const FollowButton({Key? key, this.user}) : super(key: key);
   final User? user;

Diff for: packages/stream_feed_flutter/lib/src/widgets/pages/compose_screen.dart

@@ -5,6 +5,7 @@ import 'package:stream_feed_flutter/src/widgets/activity/activity.dart';
 import 'package:stream_feed_flutter/src/widgets/buttons/reactive_elevated_button.dart';
 import 'package:stream_feed_flutter/stream_feed_flutter.dart';
 
+/// A widget to react to an activity or compose a new activity.
 class ComposeScreen extends StatefulWidget {
   const ComposeScreen(
       {Key? key,