Support i18n for Caddy documentation

[ykla]

Hello Caddy team,

I would like to suggest adding support for internationalization (i18n) in the Caddy documentation. This would make it easier for non-English speakers to read and contribute. Ideally, the documentation could support multiple languages while keeping it synchronized with the main content.

Thank you for considering this enhancement!

[francislavoie]

For chinese docs, there's this community maintained translation https://github.com/phpple/caddy2-cn-doc (not up to date though, it seems).