The guidance contradicts itself and almost none of it is dated, so here's a map of who says what, what the research supports, and how AGENTS.md fits in.
This is super cool and definitely something I can relate to. In fact, I recently built Reps, a daily coding puzzle, to help fight “skill rot” as you say. Try it out at https://reps.zander.wtf and let me know what you think.
All notes in my theme are essentially markdown, so you'd have to convert what you've got. There would be an up front cost, but I think that the benefit might be worth it. Having said that, as you can see by the discussion on this thread, each person has their own preference for how they keep notes.
For an in-depth look at all the different options for centering an element, have a look at Stephen Shaw's research on Codepen: http://codepen.io/shshaw/full/gEiDt