bug #5041 Fixed variable name in : Reference -> validation constraint…

…s -> count -> PHP (aminemat)

This PR was submitted for the 2.6 branch but it was merged into the 2.3 branch instead (closes #5041).

Discussion
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Fixed variable name in : Reference -> validation constraints -> count -> PHP

| Q                  | A
| -----------------| -------------
| Doc fix?        | yes
| New docs?   | no
| Applies to     | [2.6]
| Fixed tickets | no tickets

Commits
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55ee255 Fixed variable name in : Reference -> validation constraints -> count -> basic usage -> PHP

reference/constraints/Count.rst

@@ -88,7 +88,7 @@ you might add the following:
 
         class Participant
         {
-            public static function loadValidatorMetadata(ClassMetadata $data)
+            public static function loadValidatorMetadata(ClassMetadata $metadata)
             {
                 $metadata->addPropertyConstraint('emails', new Assert\Count(array(
                     'min'        => 1,