The other week a commenter here linked to this site as well: https://diataxis.fr/
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
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