It's very interesting to add companion guides, and the possibility to add a link from the main page is fantastic!
It would be even better if it was possible to keep the same style than the class documentation, with a table of content on the left and the "Jump to" on top for browsing in the document.
I'd like this. If nothing else, it'd be useful to give people a link to get back to the index page.
Also, the @important flag doesn't work. Not sure if this is normal.
You mean @warning?