While this is just a blog article, which is fine, I think the intended audience isn't sold on being told to run a couple of commands and install a mystery binary. (especially for those not already familiar with the Rust ecosystem and package manager)
The actual project website is here: https://martinvonz.github.io/jj/latest/
The repo is https://github.com/martinvonz/jj
Note: the project author is a Googler, and it appears to be under the umbrella of Google/Alphabet, as a CLA is required: https://martinvonz.github.io/jj/latest/contributing/