Added @rochacbrun to the AUTHORS file. MongoEngine#692

Author: Omer Katz

AUTHORS

@@ -203,4 +203,5 @@ that much better:
  * Eric Plumb (https://github.com/professorplumb)
  * Damien Churchill (https://github.com/damoxc)
  * Aleksandr Sorokoumov (https://github.com/Gerrrr)
- * Clay McClure (https://github.com/claymation)
+ * Clay McClure (https://github.com/claymation)
+ * Bruno Rocha (https://github.com/rochacbruno)