docs(ngRepeat): highlight track by expression position

Author: Narretz

src/ng/directive/ngRepeat.js

@@ -215,7 +215,9 @@
  *     more than one tracking expression value resolve to the same key. (This would mean that two distinct objects are
  *     mapped to the same DOM element, which is not possible.)
  *
- *     Note that the tracking expression must come last, after any filters, and the alias expression.
+ *     <div class="alert alert-warning">
+ *       <strong>Note:</strong> the `tracky by` expression must come last - after any filters, and the alias expression.
+ *     </div>
  *
  *     For example: `item in items` is equivalent to `item in items track by $id(item)`. This implies that the DOM elements
  *     will be associated by item identity in the array.