Added ignition with hostname example

[rbo]

https://examples.openshift.pub/cluster-lifecycle/add-node/

{
  "ignition": {
    "config": {
      "merge": [
        {
          "source": "https://xxxx:22623/config/worker",
          "verification": {}
        }
      ],
      "replace": {
        "verification": {}
      }
    },
    "proxy": {},
    "security": {
      "tls": {
        "certificateAuthorities": [
          {
            "source": "data:text/plain;charset=utf-8;base64,LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS....",
            "verification": {}
          }
        ]
      }
    },
    "timeouts": {},
    "version": "3.4.0"
  },
  "kernelArguments": {},
  "passwd": {},
  "storage": {
    "files": [
      {
        "path": "/etc/hostname",
        "contents": {
          "source": "data:,disco-worker-2"
        },
        "mode": 420
      }
    ]
  },
  "systemd": {}
}