dev-testing doc: Clarify master_fqdn and cluster_distro

Signed-off-by: Dan Mick <dan.mick@inktank.com>
calamari_rest: BOOTSTRAP_RHEL was missing sudo

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Merge pull request #191 from ceph/wip-testing-nits

Wip testing nits