title: How to add search box inside <select> tag with ng-option
body: <p>I need to add search box inside the select tag with ng-option.</p>
  
  <pre><code>    &lt;select class="form-control" ng-model="modelname" ng-options="category.id as category.name for category in Categories ng-change="getSubCategory()"&gt;
  &lt;option&gt;&lt;--search box should be here--&gt;&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>