Docs: add pinning of terraform for migration (#88528)

* Docs: update with terraform version

* added the terraform version pinning

* formatting

* Update docs/sources/administration/api-keys/index.md

Co-authored-by: Jack Baldry <jack.baldry@grafana.com>

* formatting

---------

Co-authored-by: Jack Baldry <jack.baldry@grafana.com>

docs/sources/administration/api-keys/index.md

@@ -182,6 +182,25 @@ curl --request GET --url http://localhost:3000/api/folders --header 'Authorizati
 
 ### Migrate API keys to Grafana service accounts in Terraform
 
+{{< admonition type="note" >}}
+The terraform resource `api_key` is removed from the Grafana Terraform Provider in v3.0.0.
+Before you migrate and remove the use of the resource, you should pin your terraform version to a version less-than or equal-to v2.19.0.
+For more information, refer to the [Grafana Terraform Provider release notes](https://github.com/grafana/terraform-provider-grafana/releases/tag/v3.0.0).
+{{< /admonition >}}
+
+To pin the Grafana Terraform Provider to v2.19.0:
+
+```hcl
+terraform {
+  required_providers {
+    grafana = {
+      source  = "grafana/grafana"
+      version = "2.19.0"
+    }
+  }
+}
+```
+
 This section shows you how to migrate your Terraform configuration for API keys to Grafana service accounts. For resources, see [Grafana Service Accounts in Terraform](https://registry.terraform.io/providers/grafana/grafana/latest/docs/resources/service_account_token).
 
 For migration your cloud stack api keys, use the `grafana_cloud_stack_service_account` and `gafana_cloud_stack_service_account_token` resources see [Grafana Cloud Stack Service Accounts in Terraform](https://registry.terraform.io/providers/grafana/grafana/latest/docs/resources/cloud_stack_service_account).