After several days spent at fighting with autogsdoc (GNUstep documentation system), I have finally managed to output PreferencesKit documentation in html. I'm happy to stop fiddling with it, now I understand how it works and its shortcomings.
Basically in my case it was very important to pass both headers and implementations, to have implementations following headers in autogsdoc paramaters… An another important point was to turn on both -Verbose and -Warn options and to never forget autogsdoc may fail silently without reporting any errors. When autogsdoc is stumbling on constants declared at several places, you may just process your source code files two by two (.h and .m), that's the last trick I used to output the current PreferencesKit Reference.
With some key points highlighted in documentation, I'm pretty sure it could be easier to tackle autogsdoc. I suppose I have to report the weird experiences I encountered with it ;-)
Back to the crux of the matter now… I have updated PreferencesKit page with various links :
both recently uploaded on Étoilé website.