App Health Checks page is missing description of defined behavior for when an app has multiple replicas

**What content needs to be created or modified?**
The current content for App Health Checks does not provide a description for the defined behavior of App Health Checks for applications with multiple pods running. e.g. when one pod is deemed unhealthy out of a replica set, does DAPR cut off access to all pods or just the unhealthy one ?

**Describe the solution you'd like**
I'd like to see the defined behavior for multiple-replica applications added to this page, e.g. what happens when one pod is unhealthy ? what happens when a majority of pods are unhealthy ? How does number of unhealthy pods impact delivery of Service Invocations, Pub/Sub subscriptions, etc to each of the different pods with differing health states ?

**Where should the new material be placed?**
In the existing page for App Health Checks under Operations => Resiliency => Health Checks => App Health Checks in the navigation menu for the documentation.