[connectivity] add more documentations, delete example/README (flutter#2262)

Author: Chris Yang

packages/connectivity/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.5+4
+
+* Stability and Maintainability: update documentations.
+
 ## 0.4.5+3
 
 * Remove AndroidX warnings.

packages/connectivity/example/README.md

@@ -15,6 +15,7 @@ import 'package:meta/meta.dart';
 /// None: Device not connected to any network
 enum ConnectivityResult { wifi, mobile, none }
 
+/// Discover network connectivity configurations: Distinguish between WI-FI and cellular, check WI-FI status and more.
 class Connectivity {
   /// Constructs a singleton instance of [Connectivity].
   ///
@@ -35,11 +36,13 @@ class Connectivity {
 
   Stream<ConnectivityResult> _onConnectivityChanged;
 
+  /// Exposed for testing purposes and should not be used by users of the plugin.
   @visibleForTesting
   static const MethodChannel methodChannel = MethodChannel(
     'plugins.flutter.io/connectivity',
   );
 
+  /// Exposed for testing purposes and should not be used by users of the plugin.
   @visibleForTesting
   static const EventChannel eventChannel = EventChannel(
     'plugins.flutter.io/connectivity_status',

packages/connectivity/lib/connectivity.dart

@@ -3,7 +3,7 @@ description: Flutter plugin for discovering the state of the network (WiFi &
   mobile/cellular) connectivity on Android and iOS.
 author: Flutter Team <[email protected]>
 homepage: https://github.com/flutter/plugins/tree/master/packages/connectivity
-version: 0.4.5+3
+version: 0.4.5+4
 
 flutter:
   plugin: