Any notes online you think are so perfectly written you’d put them into your markdown note vault without changing a thing?

Any notes online you think are so perfectly written you’d put them into your markdown note vault without changing a thing?

Please share a link here, can be from any subject or knowledge area. Like a summary notes for some math topic, or an analysis for a book.

For instance, I love this Git notes article the diagrams are very well drawn, and I've saved it in my notes.