add note about api enablement lag

Author: sungchun12

README.md

@@ -109,6 +109,10 @@ _Double check the secrets file is uploaded to the bucket and terraform files ref
 8. Run the first cloud build job that sets up everything in your project
 
 ```bash
+# note: enabling apis may lag behind other services
+# relying on those apis
+# rerun this command if error message reflects the above note
+
 gcloud builds submit --config=first_build.yaml
 ```