fix broken nav on less page

docs/templates/pages/less.mustache

@@ -8,7 +8,7 @@
   <h1>{{_i}}Using LESS with Bootstrap{{/i}}</h1>
   <p class="lead">{{_i}}Customize and extend Bootstrap with <a href="http://lesscss.org" target="_blank">LESS</a>, a CSS preprocessor, to take advantage of the variables, mixins, and more used to build Bootstrap's CSS.{{/i}}</p>
   <div class="subnav">
-    <ul class="nav pills">
+    <ul class="nav nav-pills">
       <li><a href="#builtWith">{{_i}}Built with Less{{/i}}</a></li>
       <li><a href="#variables">{{_i}}Variables{{/i}}</a></li>
       <li><a href="#mixins">{{_i}}Mixins{{/i}}</a></li>