document auto_initialize overriden option

Author: nykopol

reference/forms/types/button.rst

@@ -18,6 +18,8 @@ A simple, non-responsive button.
 |                      | - `label_attr`_                                                      |
 |                      | - `translation_domain`_                                              |
 +----------------------+----------------------------------------------------------------------+
+| Overridden Options   | - `auto_initialize`                                                  |
++----------------------+----------------------------------------------------------------------+
 | Parent type          | none                                                                 |
 +----------------------+----------------------------------------------------------------------+
 | Class                | :class:`Symfony\\Component\\Form\\Extension\\Core\\Type\\ButtonType` |
@@ -35,3 +37,5 @@ Options
 .. include:: /reference/forms/types/options/label_attr.rst.inc
 
 .. include:: /reference/forms/types/options/button_translation_domain.rst.inc
+
+.. include:: /reference/forms/types/options/button_auto_initialize.rst.inc

reference/forms/types/options/button_auto_initialize.rst.inc

@@ -0,0 +1,7 @@
+auto_initialize
+~~~~~~~~~~~~~~~
+
+**type**: ``boolean``  **default**: ``false``
+
+Sets whether the form should be initialized automatically. This option is
+not modifiable as buttons do not support automatic initialization.