Add https comment to nginx file (#5243)

docker/production/nginx.prod.conf

@@ -2,6 +2,9 @@
 server {
 
     # Listen for connection on (internal) port 80
+    # If you are exposing this server to the internet, you should use HTTPS!
+    # In which case, you should also set up a redirect from HTTP to HTTPS, and listen on port 443
+    # See the Nginx documentation for more details
     listen 80;
 
     real_ip_header proxy_protocol;