minor #7686 [Validation Constraint References] Fixed Collection model example (HeahDude)

This PR was merged into the 2.7 branch.

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[Validation Constraint References] Fixed Collection model example

Ref #7648.

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b1179c9 [Validation Constraint References] Fixed Collection model example

Author: xabbuh

reference/constraints/Collection.rst

@@ -38,8 +38,8 @@ of a collection individually. Take the following example::
     class Author
     {
         protected $profileData = array(
-            'personal_email',
-            'short_bio',
+            'personal_email' => '',
+            'short_bio' => '',
         );
 
         public function setProfileData($key, $value)
@@ -80,8 +80,8 @@ following:
              * )
              */
              protected $profileData = array(
-                 'personal_email',
-                 'short_bio',
+                 'personal_email' => '',
+                 'short_bio' => '',
              );
         }