Add Ruby Library section

rubygems-org-api.md

@@ -21,6 +21,19 @@ add owners, and more.
 * [Webhook Methods](#webhook): Manage notifications for when gems are pushed
 * [Misc Methods](#misc): Various other interactions with the site
 
+<a id="library"> </a>
+Ruby Library
+------------
+
+You can also interact with RubyGems.org using Ruby.
+
+The [gems](https://rubygems.org/gems/gems) client provides a Ruby interface to
+all the resources listed below. This library has
+[full documentation](http://rdoc.info/gems/gems) that includes some basic usage
+examples in the README. You can install the library with the command:
+
+    gem install gems
+
 <a id="gem"> </a>
 Gem Methods
 -----------