fix an example for google_compute_router_nat (#3768) (#2291)

Co-authored-by: Edward Sun <[email protected]>
Signed-off-by: Modular Magician <[email protected]>

Co-authored-by: Edward Sun <[email protected]>

Author: modular-magician

.changelog/3768.txt

@@ -0,0 +1,2 @@
+```release-note:none
+```

website/docs/r/compute_router_nat.html.markdown

@@ -102,7 +102,7 @@ resource "google_compute_router_nat" "nat_manual" {
   region = google_compute_router.router.region
 
   nat_ip_allocate_option = "MANUAL_ONLY"
-  nat_ips                = google_compute_address.address.*.id
+  nat_ips                = google_compute_address.address.*.self_link
 
   source_subnetwork_ip_ranges_to_nat = "LIST_OF_SUBNETWORKS"
   subnetwork {