Update some Audit documentation

Summary:
Ref T10978.

• Generally refresh this documentation.
• Use the word "publish", not the word "push", to distinguish between review and audit, echoing the language in the "Write, Review, Merge, Publish" document.
• Mention the new "Needs Verification" state.

Test Plan: Read documentation.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10978

Differential Revision: https://secure.phabricator.com/D17253