example README seems to be missing `gsutil` command

[alljames]

When following the instructions in example/README.md, I encounter an error when running terraform plan:

Error: Failed to get existing workspaces: querying Cloud Storage failed: googleapi: Error 403: terraformsa@<GCP_PROJECT>.iam.gserviceaccount.com does not have storage.objects.list access to <GCP_PROJECT>-terraform-state., forbidden

This error disappears once the following comand has been run, and terraform plan generates a plan as expected:

gsutil iam ch serviceAccount:${TF_GCP_SA}:objectAdmin gs://${GCS_TF_BUCKET}

[repo-lockdown]

This project is now deprecated so we aren't accepting any further changes.