Implement mdbook language switch feature

[raphjaph]

Would be great to have different languages for the docs, which are made with mdBook. In order to do that we would probably have to use https://github.com/google/mdbook-i18n-helpers. Unfortunately I do not have time to do that at the moment but happy to review the PR when it's done.

[DrJingLee]

This is a demo of the website.

https://ordinals.education/

[ordinaHO]

just saw your demo its great ! so with that you mean the main hand book should have a new JavaScript Code with Language Switcher and ralph will be able to add the languages , Im still trying to figure out what different mdbook helper will make for my translation.

[raphjaph]

just implemented the language picker in @DrJingLee's PR. Have a look!

[mgeisler]

Nice, thanks for setting this up! I'm adding a link back in google/mdbook-i18n-helpers#71. Feel free to raise issues in the repository if you run into problems.

[raphjaph]

Closing since we have implemented it now