fix nginx config for disallowing default IP access

etc/nginx/nginx.conf

@@ -31,6 +31,11 @@ http {
 	access_log /var/log/nginx/access.log;
 	error_log /var/log/nginx/error.log;
 
+	# https://github.com/doorkeeper-gem/doorkeeper/issues/1554#issuecomment-1304606633
+	# proxy_buffers 4 16k;
+	# proxy_buffer_size 16k;
+	# proxy_busy_buffers_size 32k;
+
 	# stats for prometheus nginx exporter
 	server {
 		listen 9181;