Update locale.rst

added 'de'

Author: mohamedGasmii

translation/locale.rst

@@ -98,7 +98,7 @@ A better policy is to include the locale in the URL using the
                 path: '/{_locale}/contact',
                 name: 'contact',
                 requirements: [
-                    '_locale' => 'en|fr',
+                    '_locale' => 'en|fr|de',
                 ],
             )]
             public function contact()