container: add emphasis of service account attribute reference in docs (#14020) (#22959)

[upstream:341dffb1a3975853d592469a3fb557de0c5e7b31]

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

website/docs/r/container_cluster.html.markdown

@@ -620,7 +620,7 @@ as "Intel Haswell" or "Intel Sandy Bridge".
 
 -> `monitoring.write` is always enabled regardless of user input.  `monitoring` and `logging.write` may also be enabled depending on the values for `monitoring_service` and `logging_service`.
 
-* `service_account` - (Optional) The Google Cloud Platform Service Account to be used by the node VMs created by GKE Autopilot or NAP.
+* `service_account` - (Optional) The `email` of the Google Cloud Platform Service Account to be used by the node VMs created by GKE Autopilot or NAP.
 
 * `boot_disk_kms_key` - (Optional) The Customer Managed Encryption Key used to encrypt the boot disk attached to each node in the node pool. This should be of the form projects/[KEY_PROJECT_ID]/locations/[LOCATION]/keyRings/[RING_NAME]/cryptoKeys/[KEY_NAME]. For more information about protecting resources with Cloud KMS Keys please see: https://cloud.google.com/compute/docs/disks/customer-managed-encryption