Looking for open source documentation generator

Good documentation can't be automated. It requires someone to carefully craft working examples of all the parameters and functions that are available, so you can copy/paste them into a program to try them out.

I'd expect at least two separate people are required... a writer and an editor.

It's not about automating the documentation. It is about the static site generators for documentation. Ex: https://docusaurus.io/

Astro has tools to build documentation from OpenAPI specs. Found it a bit easier to get started with customization compared to docusaurus.

First problem ... define what you mean by "documentation"

We talking javadocs? MSDN? IBM developerWorks? Docs.Splunk? ReadTheDocs.io? GitHub readme.md? ...?

Did you check the websites I mentioned in the description?

Yes - but that's still not automating the documentation ... it's only [potentially] automating presenting it

So ... back to my initial narrowing-down inquiry :)