R1:c71f92a1eba7

Fix new Countdown link

Summary: Correct the url for edit engine. Fixes T11046

Test Plan: new install -> clicky green button

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T11046

Differential Revision: https://secure.phabricator.com/D16078