Use Terraform to Provision Infrastructure on Linode Proposed Changes

@Rajakavitha1 is already working on this.

Since Jun 9, 2026.

The Terraform guide still uses `region = "us-south"` in its examples for Dallas, but the current Linode API returns Dallas as `us-central`.

Guide:
https://www.linode.com/docs/guides/how-to-build-your-infrastructure-using-terraform-and-linode/

Observed behavior:
- Terraform config uses `us-south`
- `terraform apply` succeeds
- `terraform state show` later reports `region = "us-central"`
- `terraform plan` then shows a diff from `us-central -> us-south`
- attempting to apply may fail with:
`Error: failed to migrate instance ... [400] [region] Cannot migrate linode to the same region`

This suggests `us-south` is still accepted as a legacy alias, but `us-central` is now the canonical Dallas region ID returned by the API.

Request:
Please update the guide examples to use `us-central` for Dallas, TX to avoid perpetual Terraform drift and same-region migration errors.