Added copyright docblocks

src/Grant/AuthCodeGrant.php

@@ -1,4 +1,11 @@
 <?php
+/**
+ * @author      Alex Bilbie <hello@alexbilbie.com>
+ * @copyright   Copyright (c) Alex Bilbie
+ * @license     http://mit-license.org/
+ *
+ * @link        https://github.com/thephpleague/oauth2-server
+ */
 
 namespace League\OAuth2\Server\Grant;