[APIM] Update backends limitations

CB and LB limitations

Author: dlepow

articles/api-management/backends.md

@@ -89,6 +89,11 @@ Starting in API version 2023-03-01 preview, API Management exposes a [circuit br
 
 The backend circuit breaker is an implementation of the [circuit breaker pattern](/azure/architecture/patterns/circuit-breaker) to allow the backend to recover from overload situations. It augments general [rate-limiting](rate-limit-policy.md) and [concurrency-limiting](limit-concurrency-policy.md) policies that you can implement to protect the API Management gateway and your backend services.
 
+> [!NOTE]
+> * Currently, the backend circuit breaker isn't supported in the **Consumption** tier of API Management.
+> * Because of the distributed nature of the API Management architecture, circuit breaker tripping rules are only approximate.
+
+
 ### Example
 
 Use the API Management [REST API](/rest/api/apimanagement/backend) or a Bicep or ARM template to configure a circuit breaker in a backend. In the following example, the circuit breaker in *myBackend* in the API Management instance *myAPIM* trips when there are three or more `5xx` status codes indicating server errors in a day. The circuit breaker resets after one hour.
@@ -177,7 +182,9 @@ Use a backend pool for scenarios such as the following:
 To create a backend pool, set the `type` property of the backend to `pool` and specify a list of backends that make up the pool.
 
 > [!NOTE]
-> Currently, you can only include single backends in a backend pool. You can't add a backend of type `pool` to another backend pool.
+> * Currently, you can only include single backends in a backend pool. You can't add a backend of type `pool` to another backend pool.
+> * Because of the distributed nature of the API Management architecture, backend load balancing is approximate.
+
 
 ### Example