add installation instructions to pkg packages

pkg/args/lib/args.dart

Index: pkg/args/lib/args.dart
diff --git a/pkg/args/lib/args.dart b/pkg/args/lib/args.dart
index 1337b46a6a8f40ac92b72a14c175eee7e8c867bb..eb0d3f49f0ed6004fa6923923302f059787ad3a1 100644
--- a/pkg/args/lib/args.dart
+++ b/pkg/args/lib/args.dart
@@ -6,6 +6,16 @@
  * This library lets you define parsers for parsing raw command-line arguments
  * into a set of options and values using [GNU][] and [POSIX][] style options.
  *
+ * ## Installing ##
+ *
+ * Use [pub][] to install this package. Add the following to your `pubspec.yaml`
+ * file.
+ *
+ *     dependencies:
+ *       args: any
+ *
+ * And then run `pub install`.

[Andrei Mouravski, 2013/04/19 20:13:35]

You're starting a sentence with "and" but it's uppercase?

Maybe say:

"... add the following to your `pubspec.yaml` file:

<stuff>

"

Then run `pub install`.

For more information, see:

* [args package on pub.dartlang.org](http://pub.dartlang.org/packages/args)
* [pub documentation](http://pub.dartlang.org/doc/)


I just saw that you have pub.dartlang.org below, but this might be useful
information up here.

[sethladd, 2013/04/19 20:32:43]

The reference to pub below is just to make the links work.

I can change And Then.

+ *
  * ## Defining options ##
  *
  * To use this library, you create an [ArgParser] object which will contain
@@ -209,6 +219,7 @@
  *
  * [posix]: http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap12.html#tag_12_02
  * [gnu]: http://www.gnu.org/prep/standards/standards.html#Command_002dLine-Interfaces
+ * [pub]: http://pub.dartlang.org
  */
 library args;