Remove gist link that (never?) doesn't work
Summary: Removing 404 link, fixes https://github.com/phacility/arcanist/issues/180
Test Plan: n/a
Reviewers: epriestley, avivey
Reviewed By: epriestley, avivey
Subscribers: Korvin, epriestley
Differential Revision: https://secure.phabricator.com/D10689