As much as I hate the excessive use of cutesy emoji, I can't help but be drawn to this kind of thing.

Of course, you could also just write out the prefix "Bugfix: ", "Security fix: ", etc. Less internationalized, but no table lookup required.

It also would not be hard to write a plug-in for whatever text editor, or your shell, that generates these.

If you do use these, you ought to include this link in your readme so that people know what the heck the emoji mean.