Simple translations fallback to de/en
Currently, there is no fallback for pages if a page is not yet translated.
We could do a simple fallback, by iterating over the german part and using this one as the canonical source. Then we could check whether a file exists and if not (if it's not in git), we could do a simple copy of the file and inject a notice header, that asks for translation.
If a translation in english exists, we could prefer this one, as it could increase the contributions.
This could be done as a pre-step in the CI.
Inspired by: https://github.com/gohugoio/hugo/issues/5612#issuecomment-585457647