update versions (properly)

Author: Jaime Melis

source/_templates/versions.html

@@ -3,7 +3,7 @@
         <b>{{ version|e }}</b><b class="caret"></b>
     </a>
     <ul class="dropdown-menu globaltoc">
-        <li><a href="/4.10">4.10 (Stable)</a></li>
+        <li><a href="/stable">Last Stable</a></li>
         <li><a href="http://opennebula.org/documentation/archives/">Previous Releases</a></li>
     </ul>
 </li>