What's the feature? Add the ability to update NextDNS.io via the DDNS updater.

Extra information? NextDNS allows the ability to update IP address information via a single url by programmatically calling the following url: https://link-ip.nextdns.io/<Endpoint ID>/<API GUID>. There is no need to provide a username/password or server. Just need to call the URL to automatically update the IP.