Update install-service.sh

Added'trusted_proxies' => 
array (
'$NEXTCLOUD_REVPROX'
),
To enable source IP detection over reverse proxy

src/nextcloud/install-service.sh

@@ -388,6 +388,10 @@ array (
 'theme' => '',
 'trashbin_retention_obligation' => 'auto, 7',
 'updater.release.channel' => 'stable',
+'trusted_proxies' => 
+array (
+'$NEXTCLOUD_REVPROX'
+),
 );
 EOF