[cratermoon]

The Grand Unified Theory of Documentation also appears at Divio's site https://documentation.divio.com/

Some additional documents that don't fit neatly into the 4-document model are

Conceptual overviews, which are kind of like explanations but lean more towards the broader theories

Case studies, focusing on practical examples in use

FAQs are kind of a reference, focusing on common problems in usage

Troubleshooting guides can cover problems too uncommon for FAQs, but they usually presume a certain level of knowledge

Best practice articles are opinionated guides supplementing explanatory documents with additional guidance on why some solutions should be idiomatic