Merge branch '6.4' into 7.1

* 6.4:
  Update service_decoration.rst

Author: javiereguiluz

service_container/service_decoration.rst

@@ -207,12 +207,20 @@ automatically changed to ``'.inner'``):
                 ->args([service('.inner')]);
         };
 
-.. tip::
+.. note::
 
     The visibility of the decorated ``App\Mailer`` service (which is an alias
     for the new service) will still be the same as the original ``App\Mailer``
     visibility.
 
+.. note::
+
+    All custom :ref:`service tags </service_container/tags>`_ from the decorated
+    service are removed in the new service. Only certain built-in service tags
+    defined by Symfony are retained: ``container.service_locator``, ``container.service_subscriber``,
+    ``kernel.event_subscriber``, ``kernel.event_listener``, ``kernel.locale_aware``,
+    and ``kernel.reset``.
+
 .. note::
 
     The generated inner id is based on the id of the decorator service