R1:93f735ed2f58

Diviner Book Index styles

Summary: Slightly more readable, less space than current index. LMK if you hate it though.

Test Plan: Look at user and dev book indexes.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6932