Archive Project?

I believe that this project [has ended](https://project-oak.github.io/rust-verification-tools/2021/09/01/retrospective.html#fn:but-also-other-things) and thus the repo should be [archived](https://github.blog/2017-11-08-archiving-repositories/) (which will make the repo read-only and put a notice at the top).  Apologies if work is still ongoing.