Add multilingual documentation structure for mdBook

[maximizemaxwell]

Currently, the documentation is written in English and built with mdBook. It would be very helpful if the docs were structured in a way that supports multiple languages (for example, using translations directories or mdBook’s [multilingual book setups](https://rust-lang.github.io/mdBook/format/summary.html#multilingual-books)).

I’m not very familiar with setting up this structure myself, but once the framework for multilingual docs is in place, I would be happy to contribute a full Korean translation right away.

This would make Candle’s documentation more accessible to non-English speakers and help grow the community further.

Thanks for considering this!

[trinhanhtuan]

Me too, whenever the framework for multilingual documents is in place, I am more than excited to contribute a full Vietnamese translation right away. Accessible to non-English speaking communities will accelerate the Candle adoption globally.

Someone in Candle team just drop us a notice.

Cordially, RustDev Vietnam