mbdns v2.0.1

mbdns v2.0.1 targets the Mythic Beasts Primary DNS API v2

• Config file format changed, be sure to look at the docs
• Look at Mythic Beasts' docs too, since you need new API key ID + key secret material to use the new endpoints
• Switched project structure to a golang module
• New -insecure flag to help debugging
• Updated documentation
• v2.0.1 release binaries built with go1.20.2 darwin/amd64
• Better error reporting for API endpoint communication failure

Tested on my UDM SE.