Update resource-health.md

Author: aimee-littleton

articles/nat-gateway/resource-health.md

@@ -40,9 +40,9 @@ To view the health of your NAT gateway resource:
 
 ## Resource health alerts
 
-Azure Resource Health alerts can notify you in near real-time when the health state of your NAT gateway resource changes. It's recommended that you set resource health alerts to notify you when your NAT gateway resource is in a **Degraded** or **Unavailable** state.
+Azure Resource Health alerts can notify you in near real-time when the health state of your NAT gateway resource changes. It's recommended that you set resource health alerts to notify you when your NAT gateway resource changes to a **Degraded** or **Unavailable** health state.
 
-When you create Azure resource health alerts for NAT gateway, Azure sends resource health notifications to your Azure subscription. You can create and customize alerts based on:
+When you create Azure resource health alerts for NAT gateway, Azure sends resource health notifications to your Azure subscription upon a change in the health state of NAT gateway. You can create and customize alerts based on:
 * The subscription affected
 * The resource group affected
 * The resource type affected (Microsoft.Network/NATGateways)