Add reverse proxy settings to management.json template (#1639)

Add grpc_set_header to the nginx example template

infrastructure_files/nginx.tmpl.conf

@@ -46,6 +46,7 @@ server {
     proxy_set_header        X-Scheme $scheme;
     proxy_set_header        X-Forwarded-Proto https;
     proxy_set_header        X-Forwarded-Host $host;
+    grpc_set_header         X-Forwarded-For $proxy_add_x_forwarded_for;
 
     # Proxy dashboard
     location / {