Fix #6561 - Better looking puppetdoc CSS for rdoc mode

From: Duncan Phillips <duncan@yola.com>

Signed-off-by: Brice Figureau <brice-puppet@daysofwonder.com>
(#6561) increase rdoc output font size and fix facts display

Signed-off-by: Brice Figureau <brice-puppet@daysofwonder.com>
Merge pull request #1729 from masterzen/tickets/master/6561

#6561 - Better looking puppetdoc CSS for rdoc mode