This is very true. Documentation is often seen as this huge task but just contributing small bits here and there definitely lightens the load.
Documentation means different things to different people. I’m a Product Manager but I do a bit of coding in my spare time (yes, I’m one of those PMs!). I often find when I return to my code months later I’ve got a completely different context/space in my head so trying to understand my logic isn’t always clear. A few notes would help me understand my own code even better — I imagine it would do wonders for anyone else trying to read it.