added slow deploy warning

Author: robm26

content/relational-migration/setup/index2.en.md

@@ -26,6 +26,8 @@ The Lambda source code project has been setup as follows
 
 
 1. Next, let's deploy the Chalice application stack.
+   The deploy may take up to three minutes, be patient.
+
 ```bash
 chalice deploy --stage relational
 ```