docs($q): fix missing bracket in the example

src/ng/q.js

@@ -42,7 +42,7 @@
  *     alert('Success: ' + greeting);
  *   }, function(reason) {
  *     alert('Failed: ' + reason);
- *   );
+ *   });
  * </pre>
  *
  * At first it might not be obvious why this extra complexity is worth the trouble. The payoff