adding FAQ for health check

Author: jeffwmartinez

articles/app-service/monitor-instances-health-check.md

@@ -202,6 +202,9 @@ Imagine you have two applications (or one app with a slot) with Health check ena
 
 If all instances of your application are unhealthy, App Service won't remove instances from the load balancer. In this scenario, taking all unhealthy app instances out of the load balancer rotation would effectively cause an outage for your application. However, the instance replacement will still occur.
 
+ ### What happens during a slot swap?
+Health check configuration is not slot-specific, so after a swap, the Health check configuration of the swapped slot will be applied to the destination slot and vice-versa. For example, if you have Health Check enabled for your staging slot the endpoint configured will be applied to the production slot after a swap. 
+
 ### Does Health check work on App Service Environments?
 
 Yes, health check is available for App Service Environment v3, but not for versions 1 or 2. If you're using the older versions of App Service Environment, you can use the [migration feature](environment/migrate.md) to migrate your App Service Environment to version 3.