When I'm programming I try to keep in mind what my future self would need. I take notes when I'm programming, and put those notes into the repo if it's a person

When I'm programming I try to keep in mind what my future self would need. I take notes when I'm programming, and put those notes into the repo if it's a personal project, or in a separate repo just for the project. Mostly those notes are of little value to anyone by myself, but having them around lets me condense my thoughts down to comments or documents useful for other team members. With a little work, I can turn my notes into a variety of other kinds of useful documentation: references, explanations, FAQs, runbooks, etc.