[connectivity] Lint for public DartDocs (flutter#2269)

Missing DartDocs were recently added to this plugin. Add a
package-specific analysis options to make sure that they don't regress
going forward.

packages/connectivity/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.5+5
+
+* Add an analyzer check for the public documentation.
+
 ## 0.4.5+4
 
 * Stability and Maintainability: update documentations.

packages/connectivity/analysis_options.yaml

@@ -0,0 +1,11 @@
+# This exists to add a lint for missing API docs just on this specific package,
+# since not all packages have coverage for all their public members yet and
+# adding it in would be non-trivial. `public_member_api_docs` should be applied
+# to new packages going forward, and ideally the main `analysis_options.yaml`
+# file as soon as possible.
+
+include: ../../analysis_options.yaml
+
+linter:
+  rules:
+    - public_member_api_docs

packages/connectivity/example/lib/main.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// ignore_for_file: public_member_api_docs
+
 import 'dart:async';
 import 'dart:io';
 

packages/connectivity/lib/connectivity.dart

@@ -8,12 +8,17 @@ import 'dart:io';
 import 'package:flutter/services.dart';
 import 'package:meta/meta.dart';
 
-/// Connection Status Check Result
-///
-/// WiFi: Device connected via Wi-Fi
-/// Mobile: Device connected to cellular network
-/// None: Device not connected to any network
-enum ConnectivityResult { wifi, mobile, none }
+/// Connection status check result.
+enum ConnectivityResult {
+  /// WiFi: Device connected via Wi-Fi
+  wifi,
+
+  /// Mobile: Device connected to cellular network
+  mobile,
+
+  /// None: Device not connected to any network
+  none
+}
 
 /// Discover network connectivity configurations: Distinguish between WI-FI and cellular, check WI-FI status and more.
 class Connectivity {

packages/connectivity/pubspec.yaml

@@ -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+4
+version: 0.4.5+5
 
 flutter:
   plugin: