[admin-guide] remove the distribution-specific commands
[admin-guide] remove the distribution-specific commands

Change-Id: I229ed9cb0d88d124bbe9a907723ca0f8d25f927c
Closes-Bug: #1609192

openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals