It's also this sort of work that's becoming less necessary with AI, for better or worse. This appears to be a crazy good guide, but I bet asking e.g. Claude to teach you about git (specific concepts or generate the whole guide outline and go wide on it) would be at least as good.
I also think if you are at the “don’t know what you don’t know” point of learning a topic it’s very hard to direct an AI to generate comprehensive learning material.
I have found that asking AI "You are an expert teacher in X. I'd like to learn about X, where should I start?" is actually wildly effective.
How will LLMs be trained if no humans are making learning materials?
If you didn't, then you won't be included the training set (obviously) and the AI would not easily know about you. Sort of how if you start a really cool company but don't make a website Google doesn't know about you and can't return you in their search results. It's valuable for Google (AI) to know about you, so it's valuable to build the sites (docs) to get indexed (trained on).