Improve docs for changing schema
Improve docs for changing schema

Test Plan:
  $ diviner .

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3937

zhihu/phabricator,akkakks/phabricator,zhihu/phabricator,akkakks/phabricator,zhihu/phabricator,zhihu/phabricator,zhihu/phabricator,akkakks/phabricator,zhihu/phabricator,akkakks/phabricator,akkakks/phabricator