fix testing with example file

Author: karolgorc

mmv1/products/compute/InstantSnapshot.yaml

@@ -55,6 +55,7 @@ examples:
     primary_resource_name: 'fmt.Sprintf("tf-test-instant-snapshot%s", context["random_suffix"])'
     vars:
       instance_name: 'instant-snapshot'
+      disk_name: 'example-disk'
 parameters:
   - name: 'sourceDisk'
     type: ResourceRef

mmv1/templates/terraform/examples/instant_snapshot_basic.tf.tmpl

@@ -1,5 +1,5 @@
 resource "google_compute_disk" "foo" {
-  name = "foo"
+  name = "{{index $.Vars "disk_name"}}"
   type = "pd-ssd"
   size = 10
 }