bump modules/README github tag reference (#2673)

updates the snippet on how to reference Fabric modules using github tags to the latest tag (`v35.0.0`).

modules/README.md

@@ -21,7 +21,7 @@ These modules are used in the examples included in this repository. If you are u
 
     ```terraform
     module "project" {
-        source              = "github.com/GoogleCloudPlatform/cloud-foundation-fabric//modules/project?ref=v13.0.0&depth=1"
+        source              = "github.com/GoogleCloudPlatform/cloud-foundation-fabric//modules/project?ref=v35.0.0&depth=1"
         name                = "my-project"
         billing_account     = "123456-123456-123456"
         parent              = "organizations/123456"