minor #12190 Move doctrine/annotations instructions (makmaoui)

This PR was merged into the 4.3 branch.

Discussion
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Move doctrine/annotations instructions

Move doctrine/annotation instructions to first example using annotation loader

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Commits
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10a3b1c Move doctrine/annotations instructions

Author: javiereguiluz

components/serializer.rst

@@ -189,6 +189,8 @@ when constructing the normalizer::
         'allow_extra_attributes' => false,
     ]);
 
+.. include:: /_includes/_annotation_loader_tip.rst.inc
+
 Deserializing in an Existing Object
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -368,8 +370,6 @@ You are now able to serialize only attributes in the groups you want::
     );
     // $obj2 = MyObj(foo: 'foo', bar: 'bar')
 
-.. include:: /_includes/_annotation_loader_tip.rst.inc
-
 .. _ignoring-attributes-when-serializing:
 
 Selecting Specific Attributes