As discuessed in on Discord this pull request adds a documentationType property to each documentation file that corresponds to the diataxis type of documentation.

I tried to decide on the YAML naming conventions, but Vitepress frontmatter endorses camelCase here: https://vitepress.dev/guide/frontmatter

One minor thought is documentationType vs documentationKind vs documentationCategory. See https://dictionary.cambridge.org/de/grammatik/britisch-grammatik/sort-type-and-kind for a distinction:

Sort, type and kind all generally mean the same thing. They are words we use to refer to a group of people or things which share the same characteristics.
[...]
We often use and that kind of thing or and that sort of thing to refer to categories.