Update compose.yml to match Docker Hub

[eosti]

Changes the location of the Caddyfile to within a conf directory instead of being directly mounted, as suggested by https://github.com/docker-library/docs/pull/2483.

This issue was found in https://github.com/caddyserver/caddy/issues/5735 and was fixed in the Docker Hub documentation, but the Caddy documentation still referred to the old method.

[francislavoie]

Thanks! I'll take a closer look "next year" 😅 in a couple days when I'm back home

[francislavoie]

Ah yeah :see_no_evil: sorry I never got back around to this

[mholt]

Haha no worries, I hadn't either!