Add copyright notice

meta-box.php

@@ -8,6 +8,21 @@
  * Author URI:  https://metabox.io
  * License:     GPL2+
  * Text Domain: meta-box
+ *
+ * Copyright (C) 2010-2025 Tran Ngoc Tuan Anh. All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 if ( defined( 'ABSPATH' ) && ! defined( 'RWMB_VER' ) ) {