update readme (#568)

Author: kerenlahav

README.md

@@ -665,7 +665,9 @@ spec:
 
 Once the `ServiceBinding` is rotated:
 
-- The `Secret` is updated with the latest credentials. The old credentials are kept in a newly-created secret named `original-secret-name-<guid>`. This temporary secret is kept until the configured deletion time (TTL) expires.
+- The `Secret` is updated with the latest credentials.
+- The old credentials are kept in a newly-created secret named `<original-secret-name>-<guid>`.
+  This temporary secret is marked with the `services.cloud.sap.com/stale` label and is kept until the configured deletion time (TTL) expires.
 
 ### Checking Last Rotation