I mean you can always just use that nifty little program that comes preinstalled with windows, called notepad. It's pretty good! Or even better, excel :D
While I'm not entirely against the idea of a simple notepad in the game, it's very low priority, and honestly unlikely to actually happen. In particular, if I did add it, it likely wouldn't be enabled on the browser version, since browsers have very strict size limits on how much data you're allowed to store in them.