Draft: Update README
The goal of this MR is to update the readme. Special attention should be paid to:
- The temporary notes: Is this the best way to handle this? I added them for completeness, but I'm guessing they will become outdated rather soon.
- I don't know how the backend tests/ test data generation have changed. Thus the readme still has the old instructions for
visdev
. This should probably be either removed or updated to reflect changes.