minor #17346 [Serializer] Remove note about installing the FrameworkExtraBundle for using annotations (ogizanagi)

This PR was merged into the 4.4 branch.

Discussion
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[Serializer] Remove note about installing the FrameworkExtraBundle for using annotations

The FrameworkExtraBundle was never required to use Serializer's annotations ; the loader is part of the component (but still requires doctrine annotations of course).

Commits
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e84000d [Serializer] Remove note about installing the FrameworkExtraBundle for using annotations

Author: javiereguiluz

serializer.rst

@@ -84,13 +84,7 @@ possible to set the priority of the tag in order to decide the matching order.
 Using Serialization Groups Annotations
 --------------------------------------
 
-To use annotations, first add support for them via the SensioFrameworkExtraBundle:
-
-.. code-block:: terminal
-
-    $ composer require sensio/framework-extra-bundle
-
-Next, add the :ref:`@Groups annotations <component-serializer-attributes-groups-annotations>`
+You can add the :ref:`@Groups annotations <component-serializer-attributes-groups-annotations>`
 to your class::
 
     // src/Entity/Product.php