downburst:
  distro: "ubuntu"
  distroversion: "12.04"
  ceph-cluster-name: ceph
  ceph-cluster-monitors: 127.0.0.1
  ceph-cluster-pool: rbd
  rbd-disks: 1
  rbd-disks-size: 20G
  disk-size: 40G
  ram: 4G
  cpus: 2
  networks:
    - source: front

Add rbd example to documentation
Add rbd example to documentation

Add an example yaml configuration to show how to attach rbd volumes
to VMs provisioned with downburst.
