minor #7903 Update resources.rst (carwynmoore)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7903).

Discussion
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Update resources.rst

Typo fix

Commits
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2c4e25d Update resources.rst

Author: xabbuh

components/validator/resources.rst

@@ -45,7 +45,7 @@ In this example, the validation metadata is retrieved executing the
         public static function loadValidatorMetadata(ClassMetadata $metadata)
         {
             $metadata->addPropertyConstraint('name', new Assert\NotBlank());
-            $metadata->addPropertyConstraint('name', new Asert\Length(array(
+            $metadata->addPropertyConstraint('name', new Assert\Length(array(
                 'min' => 5,
                 'max' => 20,
             )));