More linter's short description
Summary: Closes T9353. I think this makes all descriptions at least basically informative.
Test Plan: arc linters - I can now understand what each one is about.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin
Maniphest Tasks: T9353
Differential Revision: https://secure.phabricator.com/D14106