add abandonment remarks to AutoCompleteMessages docs (Azure#23528)

Author: zamzowd

sdk/servicebus/Azure.Messaging.ServiceBus/src/Processor/ServiceBusProcessor.cs

@@ -133,6 +133,10 @@ public class ServiceBusProcessor : IAsyncDisposable
         /// message handler triggers an exception, the message will not be automatically
         /// completed.
         /// </summary>
+        /// <remarks>
+        /// If the message handler triggers an exception and did not settle the message,
+        /// then the message will be automatically abandoned, irrespective of <see cref= "AutoCompleteMessages" />.
+        /// </remarks>
         ///
         /// <value>true to complete the message processing automatically on
         /// successful execution of the operation; otherwise, false.</value>

sdk/servicebus/Azure.Messaging.ServiceBus/src/Processor/ServiceBusProcessorOptions.cs

@@ -50,6 +50,10 @@ public int PrefetchCount
         /// should automatically complete messages after the <see cref="ServiceBusProcessor.ProcessMessageAsync"/> handler has
         /// completed processing. If the message handler triggers an exception, the message will not be automatically completed.
         /// </summary>
+        /// <remarks>
+        /// If the message handler triggers an exception and did not settle the message,
+        /// then the message will be automatically abandoned, irrespective of <see cref= "AutoCompleteMessages" />.
+        /// </remarks>
         ///
         /// <value><c>true</c> to complete the message automatically on successful execution of the message handler; otherwise, <c>false</c>.
         /// The default value is <c>true</c>.</value>

sdk/servicebus/Azure.Messaging.ServiceBus/src/Processor/ServiceBusSessionProcessorOptions.cs

@@ -37,6 +37,10 @@ public int PrefetchCount
         /// handler has completed processing. If the message handler triggers an exception,
         /// the message will not be automatically completed.
         /// </summary>
+        /// <remarks>
+        /// If the message handler triggers an exception and did not settle the message,
+        /// then the message will be automatically abandoned, irrespective of <see cref= "AutoCompleteMessages" />.
+        /// </remarks>
         ///
         /// <value><c>true</c> to complete the message automatically on successful execution of the message handler; otherwise, <c>false</c>.
         /// The default value is <c>true</c>.</value>