added "add_header Referrer-Policy "no-referrer" always;" as per official docs

rootfs/nginx/sites-enabled/nginx.conf

@@ -12,6 +12,7 @@ server {
         add_header X-Robots-Tag none;
         add_header X-Download-Options noopen;
         add_header X-Permitted-Cross-Domain-Policies none;
+        add_header Referrer-Policy "no-referrer" always;
 
         location = /robots.txt {
             allow all;