MDL-21249 improved php docs and adding copyright blocks in mod/folder

mod/folder/db/upgrade.php

@@ -38,11 +38,14 @@
  * Please do not forget to use upgrade_set_timeout()
  * before any action that may take longer time to finish.
  *
- * @package   mod-folder
- * @copyright 2009 Petr Skoda (http://skodak.org)
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @package    mod
+ * @subpackage folder
+ * @copyright  2009 Petr Skoda  {@link http://skodak.org}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+defined('MOODLE_INTERNAL') || die();
+
 function xmldb_folder_upgrade($oldversion) {
     global $CFG, $DB;