Fill out some more info functions for libphutil-specific linters

Summary: Ref T2039. It looks like "phutil-library" didn't make it over, I'll add that to the other two (unless I'm wrong and this isn't an oversight?).

Test Plan: Used `arc linters` to read help.

Reviewers: btrahan, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Maniphest Tasks: T2039

Differential Revision: https://secure.phabricator.com/D9070