Add docs for ASB 5.x in SC

Author: SzymonPobiega

servicecontrol/transports.md

@@ -27,7 +27,11 @@ Follow the link for each transport for additional information on configuration o
 
 ## Azure Service Bus
 
-In addition to the [connection string options of the transport](/transports/azure-service-bus/configuration.md#configuring-an-endpoint) the following ServiceControl specific options are available in versions 4.4 and above:
+Starting from version 6.4, ServiceControl runs Azure Service Bus transport that, by default, uses [topic-per-event topology](/transports/azure-service-bus/topology.md), as opposed to previously used [single-topic topology](/transports/azure-service-bus/topology.md?version=asbs_4). This change affects the publishing of [integration events](/servicecontrol/contracts.md). In oder to continue using the single-topic topology, the topic name has to be specified exlicitly using the `TopicName=<topic-bundle-name>` connection string option.
+
+The new topology uses event type's full name as the name of the topic to which an event is published e.g. `servicecontrol.contracts.messagefailed`. This mapping can be customized by providing the [topology description in json](/transports/azure-service-bus/configuration.md#entity-creation-topology-options) using `ServiceControl.Transport.ASBS/Toplogy` application setting or `ServiceControl_Transport_ASBS_Toplogy` environment variable.
+
+Furthermore, in addition to the [connection string options of the transport](/transports/azure-service-bus/configuration.md#configuring-an-endpoint) the following ServiceControl specific options are available in versions 4.4 and above:
 
 * `TransportType=AmqpWebSockets` - Configures the transport to use [AMQP over websockets](/transports/azure-service-bus/configuration.md#connectivity).
 * `TopicName=<topic-bundle-name>` - Specifies the [topic name](/transports/azure-service-bus/configuration.md#entity-creation) to be used by the instance. The default value is `bundle-1`.