Real documentation libraries contain material the four types do not cleanly describe. A method with no position on it is not much use on a real library, so these are our rulings.
Orientation and overview pages
Legitimate and often necessary. Treat as explanation, but place it before the tutorial rather than after it.
Examples and snippets
Distinct from how-to guides. A how-to guide answers “how do I do this”. An example shows “here is this being done”, which a reader adapts to their own situation. Keep them as their own collection rather than forcing them into guides.
FAQ
Usually a symptom rather than a document type. Each entry is a how-to, a reference lookup or an explanation that somebody could not find. Prefer fixing findability. Keep an FAQ only where the questions are genuinely about the product's shape rather than its use.
Glossary
Reference.
Changelogs and release notes
Outside the four types. They are a product record, not documentation. Link from them to the affected pages, and never let them stand in for updating those pages.
Generated API reference
Reference, but produced by tooling. The editorial work is the surrounding descriptions, the examples, and the hand-written pages that link into it.
