docs: update README

Author: peterdeme

README.md

@@ -15,7 +15,7 @@ Check out the [Terraform](https://developer.hashicorp.com/terraform/language/bac
 
 ```hcl
 module "spacelift" {
-  source = "github.com/spacelift-io/terraform-google-spacelift-selfhosted?ref=v1.1.0"
+  source = "github.com/spacelift-io/terraform-google-spacelift-selfhosted?ref=v2.0.0"
 
   region           = "europe-west1"
   project          = "spacelift-production"