Extension:RelatedSites

One of the Wikivoyage extensions. Apparently used to Add a link to a same-named article on a related site on the sidebar. See for example "Related sites" on the sidebar in North America.

Configuration
$wgRelatedSitesPrefixes is an array of interwiki prefixes of sites you would like give prominance to. For example, for Wikivoyage this is:

Feedback
Create a task on Phabricator tagged with "MediaWiki-extensions-RelatedSites".
 * Open RelatedSites issues