R1:a0f534b87c1b

Minor improvements to Diviner layout

Summary:
- Render functions as `func()` for consistency/clarity.
- Sort articles first.
- Sort case insensitively.
- Label the "no group" symbols.

Test Plan: Regenerated and examined docs.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D8480