docs: Fix license headers and REUSE information.

Change-Id: Idb49db605a090b57dcf62b97855a4cf991421602
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3f0dba2..e1d0642 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: © 2023 Matthias Andreas Benkard <code@mail.matthias.benkard.de>
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
 stages:
   - check