That blog post is pretty old. We do have a current upgrade guide here in our docs: https://caddyserver.com/docs/v2-upgrade
We also have a (sort of deprecated) wiki with some (slightly outdated) high-level improvements listed: https://github.com/caddyserver/caddy/wiki/v2:-Improvements
The official documentation at https://caddyserver.com/docs/ is up to date, and not deprecated.