"merge policy" could link to doc about how to do a good review
Originally created by @BitingBird on #9390 (Redmine)
https://tails.boum.org/contribute/merge_policy/#index4h2 could have a link to https://www.kateheddleston.com/blog/criticism-and-ineffective-feedback (a blog post that explains how to do good reviews) or http://www.cowgirlcoder.com/articles/wintech1297.htm
Feature Branch: bitingbird:contrib/9390-reviews