Merge branch 'feature/ITZBUNDPHP-3722' into 'main'

fix: add missing SPDX

See merge request gsb11/extensions/gsb_nginx_proxy!49

Documentation/ExampleNginxConfiguration.md

+<!--
+SPDX-FileCopyrightText: 2024 Bundesrepublik Deutschland, vertreten durch das BMI/ITZBund
+
+SPDX-License-Identifier: GPL-3.0-or-later
+-->
+
 # Nginx example configuration
 
 ```