Ben Gamari authored Jan 05, 2016 and Ben Gamari committed Jan 05, 2016

Various people (myself included) have complained about the lack of
useful descriptions for the various packages included in GHC's source
tree. Fix this.

Test Plan: Validate

Reviewers: austin, thomie

Reviewed By: thomie

Subscribers: angerman, ezyang

Differential Revision: https://phabricator.haskell.org/D1736