Fix command to create Vault instances

[afanrasool]

The command to create instances returns with an error as the gcloud syntax might have changed. --scopes flag is the problem and I found that this works instead:

for i in 0 1; do
  gcloud compute instances create vault-${i} \
    --async \
    --no-address \
    --boot-disk-size 100GB \
    --image-family ubuntu-1804-lts \
    --image-project ubuntu-os-cloud \
    --machine-type n1-standard-1 \
    --scopes=https://www.googleapis.com/auth/cloudkms \
    --scopes=compute-ro \
    --tags vault
done