bug symfony#6448 [Form] fixed CollectionType needless option (HeahDude)

This PR was merged into the 2.3 branch.

Discussion
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[Form] fixed CollectionType needless option

| Q | A |
|----|----|
| Branch | 2.3+ |
| Doc fix | yes |

Define the `required` option in `(entry_)options` is useless as it is overridden by the collection option.

Commits
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4de2ad9 [Form] fixed CollectionType needless option

Author: weaverryan

reference/forms/types/collection.rst

@@ -56,8 +56,7 @@ address as its own input text box::
         'type'   => 'email',
         // these options are passed to each "email" type
         'options'  => array(
-            'required'  => false,
-            'attr'      => array('class' => 'email-box')
+            'attr' => array('class' => 'email-box')
         ),
     ));