How to add my service to umdns

Installing and Using OpenWrt
1

Hi, i'm newbie and im trying to add my cups service to umdns.
i have running the service, working fine, but i dont know how to announce using umdns.

root@nails:~# cat /etc/umdns/cups.json
{ 
        "cups_631": { 
                "service": "_cups._tcp.local", 
                "port": 631, 
                        "txt": [ 
                        "path=/printers/impresora"
                        ] 
        }
}

root@nails:~# ubus call service list | jsonfilter -e "$[*]['instances'][*]['data']['mdns']"
{ "ssh_22": { "service": "_ssh._tcp.local", "port": 22, "txt": [ "daemon=dropbear" ] } }
{ "smb_445": { "service": "_smb._tcp.local", "port": 445, "txt": [ "daemon=ksmbd" ] } }

thank you

Huawei h553 with openwrr 21.02.2