chore(demo): update collapse to use prefix

Closes #4446

Author: Foxandxss

misc/demo/index.html

@@ -52,7 +52,7 @@
                 <li><a href="#getting_started">Getting started</a></li>
             </ul>
         </nav>
-        <nav class="visible-xs" collapse="!isCollapsed">
+        <nav class="visible-xs" uib-collapse="!isCollapsed">
             <ul class="nav navbar-nav">
                 <li><a href="#getting_started" ng-click="isCollapsed = !isCollapsed">Getting started</a></li>
                 <li><a href="#directives_small" ng-click="isCollapsed = !isCollapsed">Directives</a></li>