How to learn to document?

Question

infographics

On duty, you need to research the product and create some kind of documentation (dependency diagrams, flowcharts, etc.). Fortunately or unfortunately, I do not have a specialized engineering education and experience in creating documentation. I do it on a whim and, in general, it’s even understandable to others (documents are created solely for better understanding, they are not included in any reporting, etc.). The formal side of the issue does not interest me or my colleagues, but sometimes it seems to me that it is worth discovering for myself a certain layer of systematized knowledge and tools in this area, which will make life easier for me and those around me, and will also become a plus in my resume.
Hence the question, how to approach the issue correctly? Who knows good literature (eng, rus), which covers the issue in general, without touching deeply on specific modeling tools? I understand that you can just take and study UML, but now it seems to me from a practical point of view not very convenient, redundant, because. I basically document above the class level.

Answer 1

what are you documenting? the answer will largely depend on this,
even in the usual TK, the mass of additional. sections for each of which (my personal opinion) I am still developing unique concepts, approaches (based on the project architecture, the technologies used and what specifically and in what form I should express for the reader as clearly as possible with minimal explanations on my part)