Add trailing dot to cnames

This makes the behavior consistent between NS, MX, SRV and CNAME records. >If you use CNAMEs a trailing dot will now be added automatically. >This behavior is in line with other record types that use dns names. > >This breaks using subdomain paths in CNAMEs and if you are using full domain names >in CNAMEs you will need to remove the trailing dot in your config. > >`zones."example.org"."example".cname.data = "example2"`-> `example.example.org IN CNAME example2.` >You will now have to write it as: >`zones."example.org"."example".cname.data = "example2.example.org"`-> `example.example.org IN CNAME example2.example.org.`