Remove paragraph about mapping override

Because this solution only works if the bundle relies on auto_mapping. IMHO a bundle should add mapping via the dedicated compiler pass and not rely on the application configuration (`auto_mapping: true` in this case).

Author: l-vo

bundles/override.rst

@@ -53,11 +53,6 @@ inside a :doc:`compiler pass </service_container/compiler_passes>`.
 Entities & Entity Mapping
 -------------------------
 
-If a bundle defines its entity mapping in configuration files instead of
-annotations, you can override them as any other regular bundle configuration
-file. The only caveat is that you must override all those mapping configuration
-files and not just the ones you actually want to override.
-
 If a bundle provides a mapped superclass (such as the ``User`` entity in the
 FOSUserBundle) you can override its attributes and associations. Learn more
 about this feature and its limitations in `the Doctrine documentation`_.