Allow user to specify authorized networks in settings

[nick-stroud]

This change:

• Fixes error in command in instructions output
• Adds quality of life feature to allow-list ip address on cluster creation

Example:

  - id: gke_cluster
    source: community/modules/scheduler/gke-cluster
    use: [network1]
    settings:
      enable_private_endpoint: false
      master_authorized_networks:
      - display_name: my-workstation
        cidr_block: xx.xx.xx.xx/32