Suggest upgrading Phabricator for unknown Conduit methods or parameters

Summary:
This allows using new methods without the need for bumping version number.

The usage is not neccessary because we already bumped the version number for this but I wanted to have a callsite.

Test Plan:
Made a typo in method name, then:

$ arc lint --only-new 1

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4193