doc: Updated index for newer terms.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated RGW Quickstart.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated rgw.conf example.

fixes: #4608

Signed-off-by: John Wilkins <john.wilkins@inktank.com>