add note low app health probe timeout response time degrade

Signed-off-by: fabistb <[email protected]>

daprdocs/content/en/developing-applications/building-blocks/observability/app-health.md

@@ -71,6 +71,10 @@ Additionally, app health checks are impacted by the protocol used for the app ch
 | ----------------------------- | ----------------------------------- | ----------- | ------------- |
 | [`--app-protocol`]({{< ref "app-health.md#health-check-paths" >}})   | `dapr.io/app-protocol`   | Protocol used for the app channel. supported values are `http`, `grpc`, `https`, `grpcs`, and `h2c` (HTTP/2 Cleartext). | `http`  |
 
+{{% alert title="Note" color="primary" %}}
+A low app health probe timeout can classify an application as unhealthy if it experiences a sudden high load, causing the response time to degrade.
+{{% /alert %}}
+
 ### Health check paths
 
 #### HTTP