Per https://chat.civicrm.org/civicrm/pl/uchwue5dbb8pmq3kzykg85j3gw, this extension is still supported so I figured it makes sense to remove the note saying it's deprecated which led me to misinform someone in the linked thread recently.

Also copied the text from the wiki link back here (since the wiki link only added that sentence then linked back to the README), and turned it into a "here's why the extension is useful" intro paragraph.