I don't know if that's the name, so I'll explain this as if I was a child. Wiki pages with different translations, e.g. the Main Page, says in the left side of the webpage "in other languages". And it does not use the i18n template, like few wikis do. If I want to create a wiki, from scratch, how do I implement ArchWiki's interlanguage link?
Thanks in advance.
Interlanguage links are configured in the interwiki table. If $wgInterwikiMagic is set to true, interwiki links with a language code used as a prefix produce the special navigation links instead of the usual inline links.
You can view the ArchWiki configuration in https://wiki.archlinux.org/index.php/Special:Interwiki