[#3407] Re-wording things so that people don't pay too much attention to auto_initialize

Author: weaverryan

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

@@ -3,5 +3,7 @@ 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.
+An internal option: sets whether the form should be initialized automatically.
+For all fields, this option should only be ``true`` for root forms and since
+a button can't be an entire form on its own, this is set to ``false``. You
+won't need to change this option and probably won't need to worry about it.