Sample install-config.yaml includes unsupported options

Generate ignition config files for use in AWS GovCloud

    1. Create an install-config.yaml for use with AWS GovCloud based on the example
    2. Run 'openshift-install create ignition-configs'
    

    Warning is printed that platform.aws.lbType: NLB cannot be parsed

    No warnings when using sample install-config.yaml options

    It is unclear to me if this is a bug in OpenShift itself or in the docs. If the platform.aws.lbType is supposed to work, then the error is with OpenShift not parsing the yaml correctly. If this is not a supported option then the documentation should not contain it as part of the example.