IP for custom domain is hardcoded in frontend

[lionep]

Really nice project here ! Thanks for all this work !

When a user add a custom domain, the instruction displayed on the page seems to be hardcoded to the IP 192.64.116.170 here.

For self-hosted instances, it would be great if an environment variable exists to configure this IP.

Also, a CNAME record might be more appropriate instead of an A record, in case the IP of the service change.