docs(autocomplete): common issue inside of virtual repeat

* Developers might have an autocomplete component inside of a VirtualRepeat container and will wonder why the autocompletes dropdown items are not updating.

* This is because the VirtualRepeat only updates the scope bindings (rather than re-creating the autocomplete - Recycler View) and the autocomplete previously cached the results and now displays the old ones.

Closes #9815.

Author: devversion

src/components/autocomplete/js/autocompleteDirective.js

@@ -35,11 +35,34 @@ angular
  * There is an example below of how this should look.
  *
  * ### Notes
+ * **Autocomplete Dropdown Items Rendering**
+ *
  * The `md-autocomplete` uses the the <a ng-href="api/directive/mdVirtualRepeatContainer">VirtualRepeat</a>
  * directive for displaying the results inside of the dropdown.<br/>
+ *
  * > When encountering issues regarding the item template please take a look at the
  *   <a ng-href="api/directive/mdVirtualRepeatContainer">VirtualRepeatContainer</a> documentation.
  *
+ * **Autocomplete inside of a Virtual Repeat**
+ *
+ * When using the `md-autocomplete` directive inside of a
+ * <a ng-href="api/directive/mdVirtualRepeatContainer">VirtualRepeatContainer</a> the dropdown items might
+ * not update properly, because caching of the results is enabled by default.
+ *
+ * > To avoid such problems ensure that the autocomplete does not cache any results.
+ *
+ * <hljs lang="html">
+ *   <md-autocomplete
+ *       md-no-cache="true"
+ *       md-selected-item="selectedItem"
+ *       md-items="item in items"
+ *       md-search-text="searchText"
+ *       md-item-text="item.display">
+ *     <span>{{ item.display }}</span>
+ *   </md-autocomplete>
+ * </hljs>
+ *
+ *
  *
  * @param {expression} md-items An expression in the format of `item in results` to iterate over
  *     matches for your search.<br/><br/>