Add missing shortcut icon (#979)

Author: tomayac

index.html

@@ -1642,6 +1642,8 @@ <h2>
         </li>
         <li>[=shortcut item/url=]
         </li>
+        <li>[=shortcut item/icon=]
+        </li>
       </ul>
       <p>
         A user agent can use these members to assemble a context menu to be