Documentation improvement

[ghost]

• translation as feature (nearly completely missing)
• translation for developers (maybe fix minor issues)
• translation as part of the release-management (get started)
• translation for translators (misses details and parts)
  • during the "münster-meeting" we decided, that vocabularies will need to be translated within the "yaml-file".
• overwriting translations locally

[rekt-hard]

on this note, please also have a look at the docs: https://inveniordm.docs.cern.ch/maintenance/documentation/
Moving forward, we would like to standardize documentation in order to introduce a structure. The tutorials provide a great reference point on where to place certain documentation as well as where to put certain details and where to omit them :)