remove empty_data from the list of inherited options, it's documented in the overriden options section

Author: xabbuh

reference/forms/types/checkbox.rst

@@ -60,8 +60,6 @@ These options inherit from the :doc:`form </reference/forms/types/form>` type:
 
 .. include:: /reference/forms/types/options/data.rst.inc
 
-.. include:: /reference/forms/types/options/empty_data.rst.inc
-
 .. include:: /reference/forms/types/options/required.rst.inc
 
 .. include:: /reference/forms/types/options/label.rst.inc