anthos-bm-gcp-terraform - Quickstart instructions missing Service Account activation

I'm following the instructions for installing a bare metal cluster using Terraform on GCE with vxlan ([instructions](https://github.com/GoogleCloudPlatform/anthos-samples/blob/main/anthos-bm-gcp-terraform/docs/quickstart.md)).

After the `terraform apply` command finishes successfully, Outputs are generated indicating the next steps to create the bare metal cluster from the admin workstation:

```text

abm_version = "1.14.1"
admin_vm_ssh = < gcloud compute ssh tfadmin@cluster1-abm-ws0-001 --project=[REDACTED] --zone=europe-west1-b

# ------------------------------------------------------------------------------
# You must be SSH'ed into the admin host cluster1-abm-ws0-001 as tfadmin user now
# ------------------------------------------------------------------------------
> export GOOGLE_APPLICATION_CREDENTIALS=/home/tfadmin/terraform-sa.json && \
sudo -E ./run_initialization_checks.sh && \
sudo -E bmctl create config -c cluster1 && \
sudo -E cp ~/cluster1.yaml bmctl-workspace/cluster1 && \
sudo -E bmctl create cluster -c cluster1

################################################################################
EOT
```

These instructions are missing activating the relevant service account in the admin workstation machine:

```text
gcloud auth activate-service-account --key-file=terraform-sa.json
```

This step is however present in the all-in-one install [abm install script](https://github.com/GoogleCloudPlatform/anthos-samples/blob/main/anthos-bm-gcp-terraform/resources/install_abm.sh).