Bug 1692313

* Description of problem:

The installation steps to deploy a cluster using ISO isn’t very clear in our RHCS 3 installation document [1]. RHCS 2 installation guide [2] has covered this  in a better way. Can we include examples for both ways, ie, CDN and ISO ?

There is an example section for CDN that starts with :
"An example of the all.yml file can look like:"

Maybe we can add something like this after that:
~~~
If Ceph nodes cannot connect to the Red Hat Content Delivery Network (CDN), uncomment the ceph_repository_type setting and set it to iso. And specify the path to the ISO image. This approach is most frequently used in high security environments.

An example of the all.yml file using ISO can look like:

ceph_origin: repository
ceph_repository: rhcs
ceph_repository_type: iso
ceph_rhcs_iso_path: /home/rhceph-3.1-rhel-7-x86_64.iso
ceph_rhcs_version: 3
monitor_interface: eth0
public_network: 192.168.0.0/24


[1] https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/3/html-single/installation_guide_for_red_hat_enterprise_linux/index#installing-a-red-hat-ceph-storage-cluster
[2] https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/2/html-single/installation_guide_for_red_hat_enterprise_linux/index#configuring_ceph_global_settings