Manual removal of license notice + SPDX updates

Documentation/doc/scripts/html_output_post_processing.py

@@ -3,18 +3,10 @@
 # All rights reserved.
 #
 # This file is part of CGAL (www.cgal.org).
-# 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 3 of the License, or (at your option) any later version.
 #
-# Licensees holding a valid commercial license may use this file in
-# accordance with the commercial license agreement provided with the software.
-#
-# This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
-# WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
-#
-# $URL:
-# $Id:
+# $URL$
+# $Id$
+# SPDX-License-Identifier: GPL-3.0-or-later
 #
 #
 # Author(s)     : Philipp Moeller