Feature request: add i18n support

[ghost]

The current [rust by example ] only has english document.
But why not add more i18n translate document.

user can select their own language, like : France, De, Es, Jp, Zh, Kr, It

I would like to join and translate document into Zh [Simple Chinese]

[ericswpark]

@cnmade all translations for RBE is available here:

https://github.com/rust-lang/rust-by-example#translations-to-other-languages

The section also lists Chinese which might be what you're looking for?

[dalance]

Now mdbook-i18n-helpers works fine with RBE because google/mdbook-i18n-helpers#66 was fixed.
It is an internationalization plugin for mdbook which is used at Comprehensive Rust 🦀

I think that translations can be merged into this repository by the plugin and provide language selector.