Add website documentation as markdown documents in Github repo

[mts2721]

Description

AI allows quick scanning of documents for assistance in certain tasks. This is far more efficient when you have a static output such as a PDF, or markdown file, for the RAG engine to ingest.

If you expose the rendered documentation on the Quarto website as one of these format (which should be trivial considering Quarto's entire premise is multi-format publishing), then it would greatly assist the ability of users to augment their Quarto workflows with AI tools. Currently, this process would be taking place using Google search to source the information from the Quarto websites. (Unless their are export options on the documentation website, however I have not seen any).