minor #9359 Update forms.rst (ilmoralito)

This PR was submitted for the 4.0 branch but it was merged into the 2.7 branch instead (closes #9359).

Discussion
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Update forms.rst

For the purpose of making it easy to follow the guide, I think the definition of form should be maintained in this example

Commits
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283fbd0 Update forms.rst

Author: javiereguiluz

forms.rst

@@ -424,14 +424,16 @@ Validation is a very powerful feature of Symfony and has its own
         .. code-block:: html+twig
 
             {# app/Resources/views/default/new.html.twig #}
-            {{ form(form, {'attr': {'novalidate': 'novalidate'}}) }}
+            {{ form_start(form, {'attr': {'novalidate': 'novalidate'}}) }}
+            {{ form_widget(form) }}
+            {{ form_end(form) }}
 
         .. code-block:: html+php
 
             <!-- app/Resources/views/default/new.html.php -->
-            <?php echo $view['form']->form($form, array(
-                'attr' => array('novalidate' => 'novalidate'),
-            )) ?>
+            <?php echo $view['form']->start($form, array('attr' => array('novalidate' => 'novalidate') ?>
+            <?php echo $view['form']->widget($form) ?>
+            <?php echo $view['form']->end($form) ?>
 
 .. index::
    single: Forms; Built-in field types