renamed less.html to extend.html, removing all the vars and mixins

docs/templates/layout.mustache

@@ -69,9 +69,6 @@
               <li class="{{javascript}}">
                 <a href="./javascript.html">{{_i}}Javascript{{/i}}</a>
               </li>
-              <li class="{{less}}">
-                <a href="./less.html">{{_i}}LESS{{/i}}</a>
-              </li>
               <li class="divider-vertical"></li>
               <li class="{{download}}">
                 <a href="./download.html">{{_i}}Customize{{/i}}</a>
@@ -79,6 +76,9 @@
               <li class="{{examples}}">
                 <a href="./examples.html">{{_i}}Examples{{/i}}</a>
               </li>
+              <li class="{{less}}">
+                <a href="./extend.html">{{_i}}Extend{{/i}}</a>
+              </li>
             </ul>
           </div>
         </div>