bug #3433 [WIP][Reference][Form Types] Update "radio" form type (bicpi)

This PR was merged into the 2.3 branch.

Discussion
----------

[WIP][Reference][Form Types] Update "radio" form type

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | #3410

`radio`'s parent is `checkbox`, not `form`.

I need some help regarding the task *value option should be removed from this type*:
Should it really be removed? It's because I'm able to set it and it is used in the HTML output. I'm retrieving a boolean value only when I access the submitted data via the form framework but I have also access to the raw, custom value via e.g. `$request->request->get('my_checkbox')`. So maybe it should be moved to the `inherited options` instead for the `radio` field? If yes, the wording would need an update for the `value` option and if no, why keep it for the `checkbox` field?

Commits
-------

322b21e Update&Outsource "value" option & update references
be47b90 Fix parent type doc reference
22b3d0c [Reference][Form Types] Update "radio" form type

reference/forms/types/checkbox.rst

@@ -42,17 +42,7 @@ Example Usage
 Field Options
 -------------
 
-value
-~~~~~
-
-**type**: ``mixed`` **default**: ``1``
-
-The value that's actually used as the value for the checkbox. This does
-not affect the value that's set on your object.
-
-.. caution::
-
-    To make a checkbox checked by default, set the `data`_ option to ``true``.
+.. include:: /reference/forms/types/options/value.rst.inc
 
 Inherited options
 -----------------

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

@@ -0,0 +1,12 @@
+value
+~~~~~
+
+**type**: ``mixed`` **default**: ``1``
+
+The value that's actually used as the value for the checkbox or radio button.
+This does not affect the value that's set on your object.
+
+.. caution::
+
+    To make a checkbox or radio button checked by default, use the `data`_
+    option.

reference/forms/types/radio.rst

@@ -15,10 +15,9 @@ If you want to have a Boolean field, use :doc:`checkbox </reference/forms/types/
 +-------------+---------------------------------------------------------------------+
 | Rendered as | ``input`` ``radio`` field                                           |
 +-------------+---------------------------------------------------------------------+
-| Options     | - `value`_                                                          |
-+-------------+---------------------------------------------------------------------+
-| Inherited   | - `data`_                                                           |
-| options     | - `empty_data`_                                                     |
+| Inherited   | - `value`_                                                          |
+| options     | - `data`_                                                           |
+|             | - `empty_data`_                                                     |
 |             | - `required`_                                                       |
 |             | - `label`_                                                          |
 |             | - `label_attr`_                                                     |
@@ -28,29 +27,19 @@ If you want to have a Boolean field, use :doc:`checkbox </reference/forms/types/
 |             | - `error_mapping`_                                                  |
 |             | - `mapped`_                                                         |
 +-------------+---------------------------------------------------------------------+
-| Parent type | :doc:`form </reference/forms/types/form>`                           |
+| Parent type | :doc:`checkbox </reference/forms/types/checkbox>`                   |
 +-------------+---------------------------------------------------------------------+
 | Class       | :class:`Symfony\\Component\\Form\\Extension\\Core\\Type\\RadioType` |
 +-------------+---------------------------------------------------------------------+
 
-Field Options
--------------
-
-value
-~~~~~
-
-**type**: ``mixed`` **default**: ``1``
-
-The value that's actually used as the value for the radio button. This does
-not affect the value that's set on your object.
-
-.. caution::
-
-    To make a radio button checked by default, use the `data`_ option.
-
 Inherited Options
 -----------------
 
+These options inherit from the :doc:`checkbox </reference/forms/types/checkbox>`
+type:
+
+.. include:: /reference/forms/types/options/value.rst.inc
+
 These options inherit from the :doc:`form </reference/forms/types/form>` type:
 
 .. include:: /reference/forms/types/options/data.rst.inc