docs/186857: improve handbook ToC readability

[wblock at FreeBSD.org]

Synopsis: improve handbook ToC readability

Responsible-Changed-From-To: freebsd-doc->wblock
Responsible-Changed-By: wblock
Responsible-Changed-When: Tue Feb 18 20:51:15 UTC 2014
Responsible-Changed-Why: 
Take.

http://www.freebsd.org/cgi/query-pr.cgi?pr=186857