minor symfony#4038 Update rendered tag (kirill-oficerov)

This PR was submitted for the 2.5 branch but it was merged into the 2.3 branch instead (closes symfony#4038).

Discussion
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Update rendered tag

Actually Rendered as ``button`` ``submit`` tag (not ``input`` ``submit``)

Commits
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1d50ce5 removed one space
067a447 Update submit.rst

Author: weaverryan

reference/forms/types/submit.rst

@@ -10,7 +10,7 @@ submit Field Type
 A submit button.
 
 +----------------------+----------------------------------------------------------------------+
-| Rendered as          | ``input`` ``submit`` tag                                             |
+| Rendered as          | ``button`` ``submit`` tag                                            |
 +----------------------+----------------------------------------------------------------------+
 | Inherited            | - `attr`_                                                            |
 | options              | - `disabled`_                                                        |