Document interface method (#3959)

This should give a better idea of what this method is supposed to be
doing.

Builder/BuilderInterface.php

@@ -22,8 +22,10 @@ use Sonata\AdminBundle\Admin\FieldDescriptionInterface;
 interface BuilderInterface
 {
     /**
-     * @param AdminInterface            $admin
-     * @param FieldDescriptionInterface $fieldDescription
+     * Adds missing information to the given field description from the model manager metadata, and the given admin.
+     *
+     * @param AdminInterface            $admin            will be used to gather information
+     * @param FieldDescriptionInterface $fieldDescription will be modified
      */
     public function fixFieldDescription(AdminInterface $admin, FieldDescriptionInterface $fieldDescription);
 }

Builder/FormContractorInterface.php

@@ -16,7 +16,7 @@ use Symfony\Component\Form\FormBuilder;
 use Symfony\Component\Form\FormFactoryInterface;
 
 /**
- * Interface FormContractorInterface.
+ * This interface should be implemented in persistence bundles.
  *
  * @author  Thomas Rabaix <thomas.rabaix@sonata-project.org>
  */
@@ -40,6 +40,8 @@ interface FormContractorInterface extends BuilderInterface
     public function getFormBuilder($name, array $options = array());
 
     /**
+     * Should provide Symfony form options.
+     *
      * @abstract
      *
      * @param string                    $type