Add SPDX license info
In the style of:
# SPDX-FileCopyrightText: (C) 2020 - 2024, rick@vanosten.net
# SPDX-License-Identifier: GPL-2.0-or-later
But: add other people as contribs, change from-to year
In the style of:
# SPDX-FileCopyrightText: (C) 2020 - 2024, rick@vanosten.net
# SPDX-License-Identifier: GPL-2.0-or-later
But: add other people as contribs, change from-to year