Link to os-cloud-config developer docs

Now that os-cloud-config's developer docs are in a state that I'm
happy with them being rather more discoverable, link to them in
openstack-projects.html, in a new section titled "OpenStack related
projects".

Change-Id: Ifb8b92e9b51ac968febde4b24334334323bf0638

www/developer/openstack-projects.html

@@ -104,6 +104,22 @@
     </a>
    </dd>
   </dl>
+  <ul class="subsectionNav">
+   <li class="link">
+    <a>
+     OpenStack related projects
+    </a>
+   </li>
+  </ul>
+  <dl>
+   <dd>
+    <a href="http://docs.openstack.org/developer/os-cloud-config/">
+     os-cloud-config
+    </a>
+    — Provides a set of tools to perform up-front configuration for OpenStack
+       clouds, currently used primarily by TripleO.
+   </dd>
+  </dl>
  </div>
  <div class="span-12 last-right" id="subnav-right">
   <ul class="subsectionNav last-right">