Improve docs UX by letting readers decide how wide docs go & colours..

 - Docs now auto expand to suit the viewport for a better reading experience.
 - Docs now use the simple and small and not huge at all Google Code Prettify lib.
 - Code blocks' margins and padding and text size is reduced (closes several GH issues).
 - Code blocks' contrast and colours are improved for easier reading and screen printing.

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)