Ilya Maximets and blp coding-style: Few visual enhancements for the document.
Some keywords and numbers highlighted. Added few spaces to
the examples.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Latest commit b24f1e4 Nov 16, 2018