Search providers are all backed by applications. What's the application
to read the docs in /usr/share/help?
That would depend on the format, I think. A browser for HTML docs, evince for PDF, or Yelp for DocBook/Mallard.
It would probably be better to have those docs be converted to something Yelp
can read and integrated in the Help, at least for GNOME and for Workstation.
The release notes, like most of the docs written the Docs team, are already written in DocBook, which Yelp handles just fine. The docs team can also easily convert them to PDF, HTML (multi-page), HTML (single-page), and even Markdown (with the latest release of the Publican tool). In short, I don't think conversion is a problem here -- we simply need to agree on what format(s) we want, and figure out the new workflow.