[troupo]

For a documentation framework it curiously fails at explaining what is good about it, how it is different from others, and why anyone would use it.

[Symbiote]

Looks like custom themes, extensions, and inter-document links.

Similar to Antora which you will probably recognise, though Antora also draws content from multiple Git repositories.

https://antora.org/ (not built with Antora)

Showcase of sites using it: https://gitlab.com/antora/antora.org/-/issues/20

(I'm just a user.)