Add license information to files in examples/reverse-proxies/

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

examples/reverse-proxies/apache/matrix-client-element.conf

@@ -1,3 +1,8 @@
+# SPDX-FileCopyrightText: 2019 - 2024 Slavi Pantaleev
+# SPDX-FileCopyrightText: 2024 Suguru Hirahara
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
 # This is a sample file demonstrating how to set up reverse-proxy for element.example.com.
 # If you're not using Element Web (`matrix_client_element_enabled: false`), you won't need this.