Go through and update READMEs

[viktor-f]

Is your feature request related to a problem? Please describe. There are a few READMEs in this repo and some of them are a bit outdated.

Describe the solution you'd like Go through all READMEs and update them so that they are accurate again.

Describe alternatives you've considered

Additional context

Definition of done: All READMEs are accurate.