add installation instructions to pkg packages

pkg/webdriver/lib/webdriver.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library webdriver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:json' as json;
 import 'dart:uri';
 
 part 'src/base64decoder.dart';
 
 /**
  * WebDriver bindings for Dart.
  *
+* ## Installing ##
+ *
+ * Use [pub][] to install this package. Add the following to your `pubspec.yaml`
+ * file.
+ *
+ *     dependencies:
+ *       webdriver: any
+ *
+ * And then run `pub install`.
+ *
+ * ## Using ##
+ *
  * These bindings are based on the WebDriver JSON wire protocol spec
  * (http://code.google.com/p/selenium/wiki/JsonWireProtocol). Not
  * all of these commands are implemented yet by WebDriver itself.
  * Nontheless this is a complete implementation of the spec as the
  * unsupported commands may be supported in the future. Currently,
  * there are known issues with local and session storage, script
  * execution, and log access.
  *
  * To use these bindings, the Selenium standalone server must be running.
  * You can download it at http://code.google.com/p/selenium/downloads/list.
@@ skipping 16 matching lines @@
  *      id = element['ELEMENT'];
  *      return session.sendKeyStrokesToElement(id,
  *          [ 'j', 'o', 'e', ' ', 'u', 's', 'e', 'r' ]);
  *    }).then((_) {
  *      return session.submit(id);
  *    }).then((_) {
  *      return session.close();
  *    }).then((_) {
  *      session = null;
  *    });
+ *
+ * [pub]: http://pub.dartlang.org
  */
 
 void writeStringToFile(String fileName, String contents) {
   new File(fileName).writeAsStringSync(contents);
 }
 
 void writeBytesToFile(String fileName, List<int> contents) {
   new File(fileName).writeAsBytesSync(contents);
 }
 
@@ skipping 1379 matching lines @@
    *
    * 'timestamp' (int) - The timestamp of the entry.
    * 'level' (String) - The log level of the entry, for example, "INFO".
    * 'message' (String) - The log message.
    *
    * This works with Firefox but Chrome returns a 500 response due to a 
    * bad cast.
    */
   Future<List<Map>> getLogs(String type) => _post('log', { 'type': type });
 }