Remove a versionadded directive

Author: javiereguiluz

components/serializer.rst

@@ -896,10 +896,9 @@ The Serializer component provides several built-in normalizers:
 :class:`Symfony\\Component\\Serializer\\Normalizer\\BackedEnumNormalizer`
     This normalizer converts a \BackedEnum objects into strings or integers.
 
-    .. versionadded:: 5.4
+    .. note::
 
-        The ``BackedEnumNormalizer`` was introduced in Symfony 5.4.
-        PHP BackedEnum requires at least PHP 8.1.
+        The PHP BackedEnum used by ``BackedEnumNormalizer`` requires at least PHP 8.1.
 
 :class:`Symfony\\Component\\Serializer\\Normalizer\\FormErrorNormalizer`
     This normalizer works with classes that implement

serializer.rst

@@ -78,10 +78,9 @@ As well as the following normalizers:
 * :class:`Symfony\\Component\\Serializer\\Normalizer\\ProblemNormalizer`
 * :class:`Symfony\\Component\\Serializer\\Normalizer\\BackedEnumNormalizer`
 
-.. versionadded:: 5.4
+.. note::
 
-    :class:`Symfony\\Component\\Serializer\\Normalizer\\BackedEnumNormalizer`
-    was introduced in Symfony 5.4. PHP BackedEnum requires at least PHP 8.1.
+    The PHP BackedEnum used by ``BackedEnumNormalizer`` requires at least PHP 8.1.
 
 Other :ref:`built-in normalizers <component-serializer-normalizers>` and
 custom normalizers and/or encoders can also be loaded by tagging them as