R1:fbf8328d9645

Describe how to process big checkins

Summary:
I was asked question about this twice this week.
I will link the section from [[ https://secure.phabricator.com/diffusion/ARC/browse/master/src/workflow/ArcanistDiffWorkflow.php;13b64da47aff0752$853-856 | ArcanistDiffWorkflow ]] afterwards.

NOTE: I believe that I read these instructions somewhere but I couldn't find it.

Test Plan: Read.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.