I am surprised nobody mentioned the curse of knowledge: https://en.wikipedia.org/wiki/Curse_of_knowledge

It is actually a fairly well known phenomenon, certainly in educational circles. Being aware of it when you are writing any form of documentation is a first step. But even then, it is very difficult to properly assess the knowledge entry level of your audience.

Having others read through your documentation and importantly work with your documentation is a good strategy.

One thing I can also highly recommend is simply start out with a list of assumed prerequisite knowledge in your intro. Specifically things like certain environments, frameworks, etc. Bonus points for not only listing those but also linking to the documentation for those.