Add documentation and fix code review warning

Form/FormMapper.php

@@ -12,7 +12,6 @@ namespace Sonata\AdminBundle\Form;
 
 use Sonata\AdminBundle\Builder\FormContractorInterface;
 use Sonata\AdminBundle\Admin\AdminInterface;
-use Sonata\AdminBundle\Admin\FieldDescriptionInterface;
 use Symfony\Component\Form\FormBuilder;
 
 /**

Resources/doc/reference/form_help_message.rst

@@ -1,13 +1,13 @@
-Form Help Messages
-==================
+Form Help Messages and Descriptions
+===================================
 
 Help Messages
 -------------
 
-Help messages are short notes that are rendered together with form fields. They are generally used to show additional information so the user can complete the form element faster and more accurately.
+Help messages are short notes that are rendered together with form fields. They are generally used to show additional information so the user can complete the form element faster and more accurately. The text is not escaped, so HTML can be used.
 
 Example
--------
+^^^^^^^
 
 .. code-block:: php
 
@@ -25,7 +25,7 @@ Example
     }
 
 Alternative Way To Define Help Messages
----------------------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 .. code-block:: php
 
@@ -46,3 +46,25 @@ Alternative Way To Define Help Messages
         }
     }
 
+Form Group Descriptions
+-----------------------
+
+A form group description is a block of text rendered below the group title. These can be used to describe a section of a form. The text is not escaped, so HTML can be used.
+
+Example
+^^^^^^^
+
+.. code-block:: php
+
+    <?php
+    class ExampleAdmin.php
+    {
+        protected function configureFormFields(FormMapper $formMapper)
+        {
+            $formMapper
+                ->with('General', array('description' => 'This section contains general settings for the web page'))
+                    ->add('title', null, array('help'=>'Set the title of a web page'))
+                    ->add('keywords', null, array('help'=>'Set the keywords of a web page'))
+                ->end();
+        }
+    }