Nginx example: Don't try to resolve ipv6 localhost

examples/nginx-ycast.conf.example

@@ -13,6 +13,6 @@ server {
                 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                 proxy_set_header X-Forwarded-Proto $scheme;
 
-                proxy_pass http://localhost:8010;
+                proxy_pass http://127.0.0.1:8010;
         }
 }