add language / localization switching functionality on website

[mfc]

there have been various attempts to translate and localize Level Up content, however there doesn't currently seem to be a way to incorporate different languages on the website.

For example, this is a mostly translated version of the content in traditional chinese:

• https://levelup.twngo.xyz
• https://github.com/twngo/levelup

I know that there was an effort to translate Level Up content in Spanish as well (https://www.transifex.com/otf/level-up-website/).

#51 may or may not be related?

[joncamfield]

I think with the new auto deployment functionality, it would not be hard to build subdomains for language content, e.g. es.level-up.cc, zh.level-up.cc, etc. if these translations are built as branches of this repository.

The Spanish translation appears archived, and I have reached out via #154 regarding the Chinese version to test this out.