Merge pull request #6010 from phansys/entity_repo_count

Update exception message at `EntityRepository::__call()`

lib/Doctrine/ORM/EntityRepository.php

@@ -237,7 +237,7 @@ class EntityRepository implements ObjectRepository, Selectable
 
         throw new \BadMethodCallException(
             "Undefined method '$method'. The method name must start with ".
-            "either findBy or findOneBy!"
+            "either findBy, findOneBy or countBy!"
         );
     }