Fix indent for cluster version vars

[csrwng]

Current vars file generation results in a file that looks like:

---
all:
  vars:
    # Variables that are commented in this file are optional; uncommented variables
    # are mandatory.
    ...     
    openshift_aws_node_groups:
    - name: "{{ openshift_aws_clusterid }} infra group"
      group: infra
      tags:
        host-type: node
        sub-host-type: infra
        runtime: docker
        Name: "{{ openshift_aws_clusterid }}-infra"
    - name: "{{ openshift_aws_clusterid }} compute group"
      group: compute
      tags:
        host-type: node
        sub-host-type: compute
        runtime: docker
        Name: "{{ openshift_aws_clusterid }}-compute"

# ------- #
# Version #
# ------- #

openshift_release: "3.10"
oreg_url: openshift/origin-${component}:v3.10.0

which makes version vars not to get included under all.vars and ignored by ansible

[dgoodwin]

/lgtm