add installation instructions to pkg packages

pkg/scheduled_test/lib/scheduled_test.dart

 // Copyright (c) 2013, 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.
 
 // TODO(nweiz): Add support for calling [schedule] while the schedule is already
 // running.
 // TODO(nweiz): Port the non-Pub-specific scheduled test libraries from Pub.
 /// A package for writing readable tests of asynchronous behavior.
 ///
+/// ## Installing ##
+///
+/// Use [pub][] to install this package. Add the following to your
+/// `pubspec.yaml` file.
+///
+///     dependencies:
+///       scheduled_test: any
+///
+/// Then run `pub install`.
+///
+/// For more information, see the
+/// [scheduled_test package on pub.dartlang.org][pkg].
+///
 /// This package works by building up a queue of asynchronous tasks called a
 /// "schedule", then executing those tasks in order. This allows the tests to
 /// read like synchronous, linear code, despite executing asynchronously.
 ///
 /// The `scheduled_test` package is built on top of `unittest`, and should be
 /// imported instead of `unittest`. It provides its own version of [group],
 /// [test], and [setUp], and re-exports most other APIs from unittest.
 ///
 /// To schedule a task, call the [schedule] function. For example:
 ///
@@ skipping 144 matching lines @@
 /// `scheduled_test` has a built-in timeout of 30 seconds (configurable via
 /// [Schedule.timeout]). This timeout is aware of the structure of the schedule;
 /// this means that it will reset for each task in a queue, when moving between
 /// queues, or almost any other sort of interaction with [currentSchedule]. As
 /// long as the [Schedule] knows your test is making some sort of progress, it
 /// won't time out.
 ///
 /// If a single task might take a long time, you can also manually tell the
 /// [Schedule] that it's making progress by calling [Schedule.heartbeat], which
 /// will reset the timeout whenever it's called.
+///
+/// [pub]: http://pub.dartlang.org
+/// [pkg]: http://pub.dartlang.org/packages/scheduled_test
 library scheduled_test;
 
 import 'dart:async';
 
 import 'package:unittest/unittest.dart' as unittest;
 
 import 'src/schedule.dart';
 import 'src/schedule_error.dart';
 import 'src/utils.dart';
 
@@ skipping 158 matching lines @@
 
   return currentSchedule.wrapFuture(future, description);
 }
 
 // TODO(nweiz): re-export these once issue 9535 is fixed.
 unittest.Configuration get unittestConfiguration =>
   unittest.unittestConfiguration;
 void set unittestConfiguration(unittest.Configuration value) {
   unittest.unittestConfiguration = value;
 }