R1:fd20b18c2dd8

Improve lint integration documentation

Summary: Explain what lint is, how to configure it, what we ship with, etc. Also wax philosophical.

Test Plan: Generated docs, read "carefully".

Reviewers: csilvers, btrahan, vrana

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D2628