FYI that website is outdated and unmaintained. The person who worked on it left Mozilla AFAIK (would love to be proven wrong). See https://twitter.com/CubicleApril/status/1438940565916225545

The correct thing with Caddy is to _not configure anything at all_ for TLS. The defaults are the correct thing to use. If you override the defaults, then you're more at risk of bitrot due to not remembering to update your own config. Let Caddy (and the Go stdlib, really) choose what's secure.