let the guides home point to the new release series endpoints [ci skip]

guides/source/_welcome.html.erb

@@ -16,9 +16,9 @@
 <% end %>
 <p>
 The guides for earlier releases:
-<a href="http://guides.rubyonrails.org/v4.2.0/">Rails 4.2.0</a>,
-<a href="http://guides.rubyonrails.org/v4.1.8/">Rails 4.1.8</a>,
-<a href="http://guides.rubyonrails.org/v4.0.12/">Rails 4.0.12</a>,
-<a href="http://guides.rubyonrails.org/v3.2.21/">Rails 3.2.21</a> and
-<a href="http://guides.rubyonrails.org/v2.3.11/">Rails 2.3.11</a>.
+<a href="http://guides.rubyonrails.org/v4.2/">Rails 4.2</a>,
+<a href="http://guides.rubyonrails.org/v4.1/">Rails 4.1</a>,
+<a href="http://guides.rubyonrails.org/v4.0/">Rails 4.0</a>,
+<a href="http://guides.rubyonrails.org/v3.2/">Rails 3.2</a>, and
+<a href="http://guides.rubyonrails.org/v2.3/">Rails 2.3</a>.
 </p>