minor #9109 Remove out-of-context rewrite rule tip (BlueM)

This PR was submitted for the 4.0 branch but it was merged into the 2.7 branch instead (closes #9109).

Discussion
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Remove out-of-context rewrite rule tip

The `.. include:: /_includes/_rewrite_rule_tip.rst.inc` has absolutely nothing to do with the surrounding context. Having it here is confusing.

Commits
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a0b19c3 Remove out-of-context rewrite rule tip

Author: javiereguiluz

components/serializer.rst

@@ -310,8 +310,6 @@ You are now able to serialize only attributes in the groups you want::
     );
     // $obj2 = MyObj(foo: 'foo', bar: 'bar')
 
-.. include:: /_includes/_rewrite_rule_tip.rst.inc
-
 .. _ignoring-attributes-when-serializing:
 
 Ignoring Attributes