* actions: update "understanding github actions"
Take a refresh pass on the "understanding github actions" document, in
order to reinforce our CI/CD messaging and definitions, and update the
art with high-res illustrations.
* Apply suggestions from code review
Co-authored-by: Martin Lopes <martin389@github.com>
Co-authored-by: Martin Lopes <martin389@github.com>
Co-authored-by: jmarlena <6732600+jmarlena@users.noreply.github.com>