I write docs every day professionally. Even I think this is kind of dumb. You should probably write a high-level outline first, just to get your thoughts toget

I write docs every day professionally. Even I think this is kind of dumb. You should probably write a high-level outline first, just to get your thoughts together. That could be written on a napkin for all I care, or could only exist in your mental mind palace. The important part is that you have a concrete vision for what you're trying to do. It helps to get it down physically because then you can't silently change it over time. But real docs require someone to actually use the product, find exception/edge cases and actual behavior, and document those behaviors. An outline is a great starting point, but if you just try to write all of your docs beforehand, you'll frustrate the hell out of all of your users because your initial vision for a product never accurately describes the end result.