Update reference/constraints/UniqueEntity.rst

Author: docteurklein

reference/constraints/UniqueEntity.rst

@@ -117,8 +117,12 @@ used.
 repositoryMethod
 ~~~~~~~~~~~~~~~~
 
-**type**: ``string``
+**type**: ``string`` **default**: ``findBy``
 
 .. versionadded:: 2.1
+    The ``repositoryMethod`` option was added in Symfony 2.1. Before, it was always using findBy.
+
+  
+
 The name of the repository method to use for making the query to determine the
 uniqueness. If it's left blank, the findBy method will be used. This method should return a countable result.