Applied fixes requested by igorw.

doc/cookbook/translating_validation_messages.rst

 Translating Validation Messages
 ===============================
 
-When working with Symfony2 forms, a common task would be to show localized validation messages.
+When working with Symfony2 validator, a common task would be to show localized validation messages.
 
 In order to do that, you will need to register translator and point to translated resources:
 
@@ -12,7 +12,9 @@ In order to do that, you will need to register translator and point to translate
         'translation.class_path' => __DIR__ . '/vendor/symfony/src',
         'translator.messages' => array()
     ));
+    $app->before(function () use ($app) {
         $app['translator']->addLoader('xlf', new Symfony\Component\Translation\Loader\XliffFileLoader());
         $app['translator']->addResource('xlf', __DIR__ . '/vendor/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/translations/validators.sr_Latn.xlf', 'sr_Latn', 'validators');
+    });
 
 And that's all you need to load translations from Symfony2 ``xlf`` files.
\ No newline at end of file