About [[MediaWiki:Privatedomains-instructions/en]]
Ok for int, let's forget example.org.
Jack says: changing the hard-coded string reference to an ⧼...⧽ is very simple and can be done basically by anyone and I'll be happy to +2 such a patch, although I guess I'll need to do that, if no-one else is interested in this. Likewise, technically changing the domain reference is easy as pie, although IMO changing both domains to "example.com" causes confusion and some of the current meaning might be lost; the message currently tries to illustrate that you can use multiple domains to allow users from multiple domains to edit the wiki. Adhering to RFCs is good, but it doesn't mean we should throw common sense out of the window. :-)
In Gerrit at https://gerrit.wikimedia.org/r/#/c/213783/
The original message should be based on something like example.org rather than existing domains.
There should be an {{int:...}} reference in the place of "save", since we do not know what the real button text is, and it does not seem to be part of the message group.
Example.(com|net|org) is the standard example URL, that's true. I believe that the idea for this extension came from a student of the Stanford University, hence why there are Stanford references in the message. Personally I don't have a strong opinion either way, but it's nice that there are two different domains in the message, to illustrate the fact that you can allow edits from multiple domains as opposed to just one (though, well, that should be obvious).
The "save" message is MediaWiki:Saveprefs, the same used on Special:Preferences. Changing that to the {{int:}} reference in the message is OK, it's just that there are 23 instances of the message (the English one + 22 translations) which need updating.
RFC suggest that using example.com as example domain names is the best way to go. See http://www.ietf.org/rfc/rfc2606.txt for details.