Fix underline length for title

mdoutreluingne · mdoutreluingne · commit a594b1f73ecf · 2025-02-23T18:50:12.000+01:00
diff --git a/reference/constraints/Unique.rst b/reference/constraints/Unique.rst
@@ -217,7 +217,7 @@ trailing whitespace during validation.
 .. include:: /reference/constraints/_payload-option.rst.inc
 
 ``stopOnFirstError``
-~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~
 
 **type**: ``boolean`` **default**: ``true``
 
