This plugin (in fact only a general include) extends the list of
known InterWiki+: prefixes with a more complete set created from
the MeatBall+ interwiki.map.
prev << "linking/titlefix"
next >> "interwiki/editable"

You cannot modify the README.plugins file, but anyhow any ideas or suggestion should as usually get filed on BugReports, UserSuggestions or even better the README.plugins.Discussion.