Correct spelling mistake in PhabricatorAuditEditor

Summary: Closes T15267

Test Plan: Only changes to spelling.

Reviewers: O1 Blessed Committers, chris

Reviewed By: O1 Blessed Committers, chris

Subscribers: speck, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15267

Differential Revision: https://we.phorge.it/D25251