DNSimple doesn't appear to follow the typical behaviour of appending the
domain unless the CNAME is terminated with `.`
To avoid further problems, let's just explicilty use the FQDN for all
CNAMEs.
https://support.dnsimple.com/articles/cname-record/
For comparison:
```
;; ANSWER SECTION:
alerts.forkos.org. 300 IN CNAME meta01.infra.p.
```
```
;; ANSWER SECTION:
alerts.forkos.org. 181 IN CNAME meta01.infra.p.forkos.org.
meta01.infra.p.forkos.org. 181 IN A 163.172.69.160
```