Add sessions example to Service Bus Extension README (Azure#27657)

* Add sessions example to Service Bus Extension README

* PR fb

Author: JoshLove-msft

sdk/servicebus/Microsoft.Azure.WebJobs.Extensions.ServiceBus/README.md

@@ -201,6 +201,35 @@ public static async Task Run(
 }
 ```
 
+### Session triggers
+
+To receive messages from a session enabled queue or topic, you can set the `IsSessionsEnabled`
+property on the `ServiceBusTrigger` attribute. When working with sessions, you can bind to the `SessionMessageActions` to get access to the message settlement methods in addition to session-specific functionality.
+
+```C# Snippet:ServiceBusBindingToSessionMessageActions
+[FunctionName("BindingToSessionMessageActions")]
+public static async Task Run(
+    [ServiceBusTrigger("<queue_name>", Connection = "<connection_name>", IsSessionsEnabled = true)]
+    ServiceBusReceivedMessage[] messages,
+    ServiceBusSessionMessageActions sessionActions)
+{
+    foreach (ServiceBusReceivedMessage message in messages)
+    {
+        if (message.MessageId == "1")
+        {
+            await sessionActions.DeadLetterMessageAsync(message);
+        }
+        else
+        {
+            await sessionActions.CompleteMessageAsync(message);
+        }
+    }
+
+    // We can also perform session-specific operations using the actions, such as setting state that is specific to this session.
+    await sessionActions.SetSessionStateAsync(new BinaryData("<session state>"));
+}
+```
+
 ### Binding to ServiceBusClient
 
 There may be times when you want to bind to the same `ServiceBusClient` that the trigger is using. This can be useful if you need to dynamically create a sender based on the message that is received.

sdk/servicebus/Microsoft.Azure.WebJobs.Extensions.ServiceBus/tests/Samples/BindingToSessionMessageActions.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using Azure.Messaging.ServiceBus;
+using Microsoft.Azure.WebJobs.ServiceBus;
+using System.Threading.Tasks;
+
+namespace Microsoft.Azure.WebJobs.Extensions.ServiceBus.Tests.Samples
+{
+    public static class BindingToSessionMessageActions
+    {
+        #region Snippet:ServiceBusBindingToSessionMessageActions
+        [FunctionName("BindingToSessionMessageActions")]
+        public static async Task Run(
+            [ServiceBusTrigger("<queue_name>", Connection = "<connection_name>", IsSessionsEnabled = true)]
+            ServiceBusReceivedMessage[] messages,
+            ServiceBusSessionMessageActions sessionActions)
+        {
+            foreach (ServiceBusReceivedMessage message in messages)
+            {
+                if (message.MessageId == "1")
+                {
+                    await sessionActions.DeadLetterMessageAsync(message);
+                }
+                else
+                {
+                    await sessionActions.CompleteMessageAsync(message);
+                }
+            }
+
+            // We can also perform session-specific operations using the actions, such as setting state that is specific to this session.
+            await sessionActions.SetSessionStateAsync(new BinaryData("<session state>"));
+        }
+        #endregion
+    }
+}