Include `X-Forwarded-Proto` in nginx sample [skip ci]

README.md

@@ -463,6 +463,7 @@ server {
 	location / {
 	    proxy_set_header X-Real-IP $remote_addr;
 	    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+	    proxy_set_header X-Forwarded-Proto $scheme;
 	    proxy_set_header Host $host;
 	    proxy_set_header X-NginX-Proxy true;
 	    proxy_pass http://localhost:5000;