minor #8513 Form - fix wrong submit button label (nclsHart)

This PR was merged into the 2.7 branch.

Discussion
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Form - fix wrong submit button label

The screenshot and submit button label was talking about "Post" but the form is about creating a "Task".

See #7114.

Commits
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623b20a Form - fix wrong submit button label

Author: xabbuh

_images/form/simple-form.png

@@ -93,7 +93,7 @@ from inside a controller::
             $form = $this->createFormBuilder($task)
                 ->add('task', 'text')
                 ->add('dueDate', 'date')
-                ->add('save', 'submit', array('label' => 'Create Post'))
+                ->add('save', 'submit', array('label' => 'Create Task'))
                 ->getForm();
 
             return $this->render('default/new.html.twig', array(