Added topic Controller overview with images.

This is Moitrayee's patch but rebased by Colin Dixon in the hopes of getting
it to build this time.

Change-Id: I266e697e30d5edfda4c4b5c3621b00759e247536
Signed-off-by: Moitrayee <mborah@Brocade.com>
Signed-off-by: Colin Dixon <colin@colindixon.com>
Merge "Added topic Controller overview with images."