Documentation in ember.js repo

I want to contribute to ember.js and want to make a PR for these two issues.

https://github.com/emberjs/ember.js/issues/20102 https://github.com/emberjs/ember.js/issues/19896

However, I am not able to find the documentation in the repo. My assumption is that the documentation is built from the source files. Could anyone please guide me on what should I be looking into?