fix: Correction on usage parameters (#4)

Author: James H. Nguyen

README.md

@@ -15,9 +15,10 @@ module "composer" {
   source  = "terraform-google-modules/composer/google"
   version = "~> 0.1"
 
-  project_id  = "<PROJECT ID>"
-  name        = "composer-env-test"
-  region      = "us-central1"
+  project_id        = "<PROJECT ID>"
+  region            = "us-central1"
+  composer_env_name = "composer-env-test"
+  composer_sa       = "project-service-account@<PROJECT_ID>.iam.gserviceaccount.com"
 }
 ```