nixos/caddy: change `acmeCA` default to `null`

The nixos/caddy module is somewhat old by now
and has undergone quite some refactors.
This specific module option (originally named
`ca`) used to make a bit more sense when
Caddy did not have multiple ACME CAs as
fallback (LE & ZeroSSL) by configured by
default yet (ZeroSSL came with v2.3.0).

I also rephrased the description slightly,
to mention Caddy's automatic issuer fallback
and a note which this option maps to in the
Caddyfile, to provide a bit more context and
a more up-to-date recommendation.

Specifically that "fine-grained configuration"
section comes from a time when this module did
some custom tls/issuer config json merging
with the templated Caddyfile using `jq`.

The "The URL to the ACME CA's directory"
section is a word-for-word copy from the
official Caddy docs, which also include a link
to LE's docs to the referenced staging
endpoint. So I added that as well.

0 files changed, 0 insertions, 0 deletions