Documentation is very useful today (to clarify our thoughts on what is useful and what is not, what is in scope and what is not), and for our future selves.
Writing small bits of software made me appreciative of the work teams put on large pieces of infrastructure!
Hard agree on helping out your future self. I routinely drop a commands.md file in every project now, and dump any commands in there for creating the dev environment, the build step, any thoughts that might help when I come back in five years.