This might be unusual but I would prefer to read someone's mental model of how the code works than the code itself. With thousands of files and thousands of lines of code it's difficult for me to work out how the code fits together. If you document your mental model of how the code works, I can probably map the code to your mental model and understand the code. I want/like people to create "entrypoint" packages/folde…
"Show me your flowchart and conceal your tables, and I shall continue to be mystified. Show me your tables, and I won't usually need your flowchart; it'll be obvious." -- Fred Brooks, The Mythical Man Month (1975)
Its always mystifying to me how often programmers try to show me a new concept in their code starting with some complex functions. Start with your data structures. What data are you storing, why, and when? If you show me that, the code that actually moves that data around is usually pretty obvious. (And if not, your code will be 10x easier to understand once I understand the context).