Documentation translation

[niccokunzmann]

I really value it if the docs are not just English. Personally, I created https://open-web-calendar.quelltext.eu/ which is a Markdown documentation site integrated with Weblate.

My proposal would be to

• [x] migrate to a documentation theme that allows language - we are using vitepress, DONE
• [ ] ask if pixelfed docs can be hosted on weblate
• [ ] create a translation project for that
• [ ] allow people to translate the site, adding link to hosted weblate in the right places

Personally, I start with #131 and we will see how far I get. This also requires trust and maybe upvotes if anyone else likes localized docs.