These files comprise v2.wp-api.org. The endpoint documentation is programmatically, but manually, generated from the API.
You should have Ruby and gem installed.
Install gem dependencies
bundle install
Build the endpoint documentation:
ruby regenerate.rb
Run the website locally, and recompile files on change
bundle exec jekyll serve --watch
Open http://0.0.0.0:4000 in your browser to see the site
Styles use of Foundation v 5.5.3