The title is a bit over dramatic but, per the title, if you could contribute with one piece of knowledge to a book that every single individual should learn from in order to kickstart a civilization, what would be yours?
My personal choice would be the process of soap making, from scratch.
I can periodically dust the book. When I’m not dusting, I can stand somewhere conspicuous, and say “This way to the book” if asked.
Can I give you holiday cover? I’d like this job, like some sort of holy librarian.
The All Mighty Guardian of the Book, Keeper of Knowledge.
You will also be required to know it by memory cover to cover and read it on request for anyone.