v2: acme-dns-tiny: if a CNAME is defined on _acme-challenge.example.org following it to decide where to install the TXT records
v2: acme-dns-tiny: if a CNAME is defined on _acme-challenge.example.org following it to decide where to install the TXT records

Limitation: it only follows one CNAME for the moment, maybe we should
go through CNAME chain, but it will requires to detect CNAME loop too.

Trim/acme-dns-tiny