I've been using GitHub issues for this for a couple of years, and I really like it.
Any time I run into a bug, no matter how minor, I open an issue for it. I then use comments on that issue to track every step I use to fix it - adding screenshots, pasting in blocks of command-line output, linking to debugging tools I use etc.
I usually end up with an issue thread with a dozen or so comments, all by me. I often refer back to old issue threads to remind myself how I debugged something.
Any time I run into a bug, no matter how minor, I open an issue for it. I then use comments on that issue to track every step I use to fix it - adding screenshots, pasting in blocks of command-line output, linking to debugging tools I use etc.
I usually end up with an issue thread with a dozen or so comments, all by me. I often refer back to old issue threads to remind myself how I debugged something.
Here's an example from yesterday: https://github.com/simonw/datasette/issues/1124