Hi!
This works for the Wikipedia URL given above, but many other don't return a result, for instance:
https://en.wikipedia.org/wiki/Getty_Thesaurus_of_Geographic_Names => should be http://www.wikidata.org/entity/Q1520117
This one is actually recorded as https://en.wikipedia.org/wiki/Getty%20Thesaurus%20of%20Geographic%20Names
Not sure if it's a problem or not. But the sitelinks should be updated now.