Fix diviner symbols documentation

Summary: Fixes T9267. Removes preceeding r.

Test Plan: Ran Sample, did not get error.

Reviewers: epriestley, joshuaspence

Reviewed By: epriestley, joshuaspence

Subscribers: Korvin

Maniphest Tasks: T9267

Differential Revision: https://secure.phabricator.com/D14000