doc: Fixed hyperlink.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated for hostname -s and resolving to non-loopback IP address.

fixes: #6234

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
Merge branch 'master' of https://github.com/ceph/ceph