[Config] Add \Symfony\Component\Config\Loader::load() return type

src/Symfony/Component/Config/Loader/LoaderInterface.php

@@ -24,6 +24,8 @@ interface LoaderInterface
      * @param mixed       $resource The resource
      * @param string|null $type     The resource type or null if unknown
      *
+     * @return mixed
+     *
      * @throws \Exception If something went wrong
      */
     public function load($resource, $type = null);