minor #13853 Update serializer.rst (zairigimad)

This PR was submitted for the 5.0 branch but it was squashed and merged into the 4.4 branch instead.

Discussion
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Update serializer.rst

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Commits
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ee696ea Update serializer.rst

Author: javiereguiluz

components/serializer.rst

@@ -1257,7 +1257,7 @@ These are the options available:
     Sets the root node name (default: ``response``).
 
 ``remove_empty_tags``
-    If set to true, removes all empty tags in the generated XML.
+    If set to true, removes all empty tags in the generated XML (default: ``false``).
 
 Handling Constructor Arguments
 ------------------------------