Add etcd configuration steps for RHEL and CentOS
Add etcd configuration steps for RHEL and CentOS

Closes-Bug: #1740233

Change-Id: I59de4a7bf009a866c978512c6466803ba850f9c1
Signed-off-by: blkart <1085ae7ac5d420d52a04a26b37297224b6df9d8b@gmail.com>

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals