Somewhat unrelated, it would be great to have a Medium-style highlight feature for codebases, where you could onboard developers toward excellent practice by highlighting good code in a repository that consists of various levels of code.
We have people sometimes produce the software equivalent of a Picasso, but it so rarely comes to light, and even more rarely codified to guidelines/standard-practice.
Would be very good to have "greatest-hits" of a company's codebase, that could serve as internal knowledge-sharing.
https://github.com/github/hub/blob/master/github/crash_repor...
Or do you mean with comments in the margin?