Is there any way we could add, or link to, some supplementary local information, at the page that was transcluded from mediawiki.org? Eg. mw:Help:User page would go everywhere, but then en:Help:User page could add some additional sections at the bottom.
(Afaik this is impossible, and any wiki that wanted supplementary info would need to create a local copy and add it to that.)
Maybe the mw pages could have a template that would create some kind of "{{SITENAME}} specific" link, that would appear only if an equivalent page exists locally?
For example, at LocalWiki you would have:
Help:MediaWiki/User_page (an automatic copy of mw:Help:User page).Help:User_page (an optional page created manually with local specific info).The Help:MediaWiki/etc part would identify the MW generic help pages. This idea would need a lot of polish, but at least would allow a reasonable integration between generic and local help docs.