On this page:
https://readium.org/architecture/projects
The link under Web -> Navigator goes to
https://github.com/evidentpoint/r2-navigator-web
It seems like it should probably go to
https://github.com/readium/r2-navigator-web
However, I didn't want to submit a pull request in case this done on purpose.
The "Shared Model" link has the same substitution.