[FAB-4499] Reformatting doc
[FAB-4499] Reformatting doc

Made some corrections and reformatting to doc,
and did some clean up of no longer relevant
information. Added a section on pulling docker
images from docker hub.

Change-Id: Ie12c4354778e878c7c6f8f48d913f90094de73bd
Signed-off-by: Saad Karim <d1da09defa5b48f678dafc09ede657abebbe94c4@us.ibm.com>

saadk10/fabric-ca,saadk10/fabric-ca