feature #5702 Added a reference to the Foundation form theme (totophe)

This PR was squashed before being merged into the 2.8 branch (closes #5702).

Discussion
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Added a reference to the Foundation form theme

| Q | A |
|---|---|
| Doc fix? | no |
| New docs? | yes |
| Applies to | N/A |

See pull request: symfony/symfony#12587

Commits
-------

23c7798 Added a reference to the Foundation form theme

Author: xabbuh

cookbook/form/form_customization.rst

@@ -113,6 +113,9 @@ fragment needed to render every part of a form:
 * `bootstrap_3_horizontal_layout.html.twig`_, it's similar to the previous theme,
   but the CSS classes applied are the ones used to display the forms horizontally
   (i.e. the label and the widget in the same row).
+* `foundation_5_layout.html.twig`_, wraps each form field inside a ``<div>`` element
+  with the appropriate CSS classes to apply the default `Foundation CSS framework`_
+  styles.
 
 .. caution::
 
@@ -1087,3 +1090,5 @@ more details about this concept in Twig, see :ref:`twig-reference-form-variables
 .. _`bootstrap_3_layout.html.twig`: https://github.com/symfony/symfony/blob/master/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_3_layout.html.twig
 .. _`bootstrap_3_horizontal_layout.html.twig`: https://github.com/symfony/symfony/blob/master/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_3_horizontal_layout.html.twig
 .. _`Bootstrap 3 CSS framework`: http://getbootstrap.com/
+.. _`foundation_5_layout.html.twig`: https://github.com/symfony/symfony/blob/master/src/Symfony/Bridge/Twig/Resources/views/Form/foundation_5_layout.html.twig
+.. _`Foundation CSS framework`: http://foundation.zurb.com/