I have a reference doc in Google Docs that has links to all sorts of materials used in developing the Html2Wiki extension. Convert that doc and post to mw as a subpage to the extension. It would serve as a tool for anyone who wants to help develop the extension.
Existing documentation is sufficient.
See https://www.mediawiki.org/wiki/Extension:Html2Wiki for installation etc. The aforementioned 'Reference' doc is a series of links for developers who want to get familiar with developing MediaWiki extensions and the underlying subject matter of HTML DOM parsing, and some of the investigations I did while developing the Html2Wiki extension.