Changed default parameters to AAD Client Secret and updated confirmation message

Author: Sudhakara Reddy Evuri

src/ResourceManager/Compute/Commands.Compute/Extension/AzureDiskEncryption/SetAzureDiskEncryptionExtension.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Azure.Commands.Compute.Extension.AzureDiskEncryption
     [Cmdlet(
         VerbsCommon.Set,
         ProfileNouns.AzureDiskEncryptionExtension,
-        DefaultParameterSetName = aadClientCertParameterSet)]
+        DefaultParameterSetName = aadClientSecretParameterSet)]
     [OutputType(typeof(PSComputeLongRunningOperation))]
     public class SetAzureDiskEncryptionExtensionCommand : VirtualMachineExtensionBaseCmdlet
     {

src/ResourceManager/Compute/Commands.Compute/Properties/Resources.Designer.cs

@@ -456,7 +456,7 @@ The file needs to be a PowerShell script (.ps1 or .psm1) or a ZIP archive (.zip)
     <value>Enable AzureDiskEncryption on the VM</value>
   </data>
   <data name="EnableAzureDiskEncryptionConfirmation" xml:space="preserve">
-    <value>This cmdlet will enable encryption on the VM which may reboot the machine. Please save your work on the VM before confirming. Do you want to continue?</value>
+    <value>This cmdlet prepares the VM and enables encryption which may reboot the machine and takes 10-15 minutes to finish. Please save your work on the VM before confirming. Do you want to continue?</value>
   </data>
   <data name="VMOSDiskDiskEncryptionBothKekVaultIdAndKekUrlRequired" xml:space="preserve">
     <value>You have to specify either both of KeyEncryptionKeyVaultId and KeyEncryptionKeyUrl or none of them.</value>