Update nginx.conf

install/deb/nginx/nginx.conf

@@ -137,6 +137,7 @@ http {
     fastcgi_cache_methods GET HEAD;
     fastcgi_cache_use_stale updating error timeout invalid_header http_500 http_503;
     fastcgi_ignore_headers Cache-Control Expires Set-Cookie;
+    add_header X-FastCGI-Cache $upstream_cache_status;
 
     # Cache bypass
     map $http_cookie $no_cache {