Revert "Update serializer.rst"

This reverts commit 4d6da00.

Author: OskarStark

components/serializer.rst

@@ -624,7 +624,7 @@ If you are using isser methods (methods prefixed by ``is``, like
 ``App\Model\Person::isSportsperson()``), the Serializer component will
 automatically detect and use it to serialize related attributes.
 
-The `ObjectNormalizer` also takes care of methods starting with ``has``, ``add``
+The ``ObjectNormalizer`` also takes care of methods starting with ``has``, ``add``
 and ``remove``.
 
 Using Callbacks to Serialize Properties with Object Instances