[Relay] added upcoming breaking change message. (Azure#20930)

* [Relay]add breaking change for cmdlets.

* [Relay]updated changelog.md.

* [Relay]add target version for breaking change.

Author: LucasYao93

src/Relay/Relay/ChangeLog.md

@@ -18,6 +18,9 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Added breaking change message for cmdlets.
+    * `Set-AzRelayNamespace`
+    * `Get-AzRelayOperation`
 
 ## Version 1.0.3
 * Update references in .psd1 to use relative path

src/Relay/Relay/Cmdlets/Namespace/SetAzureRelayNamespace.cs

@@ -14,6 +14,7 @@
 using Microsoft.Azure.Commands.Relay.Models;
 using Microsoft.Azure.Commands.ResourceManager.Common.ArgumentCompleters;
 using Microsoft.Azure.Commands.ResourceManager.Common.Tags;
+using Microsoft.WindowsAzure.Commands.Common.CustomAttributes;
 using System.Collections;
 using System.Collections.Generic;
 using System.Management.Automation;
@@ -23,6 +24,7 @@ namespace Microsoft.Azure.Commands.Relay.Commands.Namespace
     /// <summary>
     /// 'Set-AzRelayNamespace' Cmdlet updates the specified Relay Namespace
     /// </summary>
+    [GenericBreakingChange("Set-AzRelayNamespace will be removed in an upcoming breaking change release, you can use Update-AzRelayNamespace in a future release", "2.0.0")]
     [Cmdlet("Set", ResourceManager.Common.AzureRMConstants.AzureRMPrefix + "RelayNamespace", SupportsShouldProcess = true), OutputType(typeof(PSRelayNamespaceAttributes))]
     public class SetAzureRelayNamespace : AzureRelayCmdletBase
     {

src/Relay/Relay/Cmdlets/Operations/GetAzureRelayOperations.cs

@@ -17,12 +17,14 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Management.Automation;
+using Microsoft.WindowsAzure.Commands.Common.CustomAttributes;
 
 namespace Microsoft.Azure.Commands.Relay.Commands.Namespace
 {
     /// <summary>
     /// 'Get-AzRelayOperation' Cmdlet retrive the Operations List
     /// </summary>
+    [GenericBreakingChange("Get-AzRelayOperation will be removed in an upcoming breaking change release. Please use 'Get-AzProviderOperation Microsoft.Relay/*'", "2.0.0")]
     [Cmdlet("Get", ResourceManager.Common.AzureRMConstants.AzureRMPrefix + "RelayOperation"), OutputType(typeof(PSOperationAttributes))]
     public class GetAzureRmRelayOperation : AzureRelayCmdletBase
     {