minor #21073 Update custom_constraint.rst (pmoradei)

This PR was submitted for the 7.3 branch but it was merged into the 6.4 branch instead.

Discussion
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Update custom_constraint.rst

grammar fix

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Commits
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4ac67ef Update custom_constraint.rst

Author: javiereguiluz

validation/custom_constraint.rst

@@ -328,7 +328,7 @@ define those options as public properties on the constraint class::
     }
 
 Then, inside the validator class you can access these options directly via the
-constraint class passes to the ``validate()`` method::
+constraint class passed to the ``validate()`` method::
 
     class FooValidator extends ConstraintValidator
     {