[docs] Add bootstrap-collapse plugin, fixing collapsing navbar.

docs/template.html

@@ -143,6 +143,7 @@ margin-top: 5px;
     <script src="{{ base_url }}/js/jquery.js"></script>
     <script src="{{ base_url }}/js/bootstrap-dropdown.js"></script>
     <script src="{{ base_url }}/js/bootstrap-scrollspy.js"></script>
+    <script src="{{ base_url }}/js/bootstrap-collapse.js"></script>
     <script>
       //$('.side-nav').scrollspy()
       var shiftWindow = function() { scrollBy(0, -50) };