Fix typo (visjs#2622)

Author: ypid

docs/timeline/index.html

@@ -1592,7 +1592,7 @@ <h2 id="Events">Events</h2>
         </ul>
       </td>
       <td>Fired after the user selects or deselects items by tapping or holding them.
-        When a use taps an already selected item, the select event is fired again.
+        When a user taps an already selected item, the select event is fired again.
         Not fired when the method <code>setSelection</code>is executed.
       </td>
     </tr>