Setting up REUSE: add copyright statements to files in examples/

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

examples/reverse-proxies/nginx/matrix.conf

@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2024 MDAD Team and contributors
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
 server {
     # TODO: once per IP and port you should add `reuseport`, if you don't have that in any other nginx config file, add it here by uncommenting the lines below and commenting the one after with `quic` but without `reuseport`
     #listen 443 quic reuseport;