bug #12672 fix reference (xabbuh)

This PR was merged into the 5.0 branch.

Discussion
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fix reference

fixes #12669

Commits
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2d83d71 fix reference

Author: wouterj

forms.rst

@@ -880,7 +880,7 @@ option in the options field array::
 
 .. seealso::
 
-    Besides guessing the form type, Symfony also guesses `validation constraints <validating-forms>`_
+    Besides guessing the form type, Symfony also guesses :ref:`validation constraints <validating-forms>`
     if you're using a Doctrine entity. Read :ref:`automatic_object_validation`
     guide for more information.