Very generous! Fwiw I bet you could make significant money (5 figures) if you made a longer version and charged in the $20-50 realm. It's hard to find quality up-to-date resources on these topics and the info is extremely valuable--the interest on HN attests to this. Also totally cool if that's not interesting to you or not your thing :)

If you change your mind, it shouldn’t be hard to handle the taxes; I think the approach would be the same as for hobby income.

If you’re in the US and filing taxes as a employee I think you’d just sum up the book sales and stick that under Other Income. If you’re already filing as a business or self employed, just roll it in no? Of course, other countries are available.

Anyway, I’d happily pay a few bucks at the very least for this. If it’s useful, it’s going to help my own income. If I see people who maybe can’t afford a few bucks can get it for free, I’ll be even happier to pay.