Add German copy for website

[candu]

Description We don't yet have German copy for the website, but we at least have a precedent in international-jugger-council/ijc-website#6 for integrating multilingual copy into the IJC website.

This is a tracking task for progress here.

Acceptance Criteria

• [x] get copy written for German version of site;
• [x] remove captive "hey, we're translating this!" modal from German language;
• [ ] add German copy to:
  • [ ] main page;
  • [ ] about;
  • [ ] play;
• [ ] make sure nav items match headings on pages.

[valkyriesavage]

There is already information for this, it just needs to be structured/added: https://docs.google.com/document/d/1_AI67yhuWV1OO8xHNsjOn7Dj4vZiGCUIqKzez0Ub3jY/edit?usp=sharing

[ArturoAresius]

It should also be made sure that the "please help us translate" pop up is moved to appear when clicking a 4th language button named "others", so that people can offer us help to get the work done