Inspired by #48 and #42 based on https://docs.microsoft.com/en-us/pow…

…ershell/module/microsoft.powershell.core/about/about_preference_variables?view=powershell-7.1 it seems that to suppress the warning the Cmdlet should be invoked with `-WarningAction SilentlyContinue` or have `$WarningPreference` set to `SilentlyContinue`.

src/NServiceBus.PowerShell/Cmdlets/InstallPlatformLicense.cs

@@ -9,6 +9,7 @@
     using RegistryView = Helpers.RegistryView;
 
     [Cmdlet(VerbsLifecycle.Install, "NServiceBusPlatformLicense", DefaultParameterSetName = "ByLicenseFile")]
+    [Obsolete(@"The default location for reading license information has changed from the registry to the file system. See https://docs.particular.net/search?q=license. This Cmdlet will be removed in NServiceBus.PowerShell v6.0.0")]
     public class InstallPlatformLicense : CmdletBase
     {
         [Parameter(Mandatory = true, HelpMessage = "Platform license file to import", Position = 0, ParameterSetName = "ByLicenseFile")]
@@ -19,6 +20,11 @@ public class InstallPlatformLicense : CmdletBase
         [ValidateNotNullOrEmpty]
         public string LicenseString { get; set; }
 
+        protected override void BeginProcessing()
+        {
+            WriteWarning("Installing license information in the registry has been deprecated as the Particular Platform reads license info from file system. For legacy installations this cmdlet can still be used. Use -Force to suppress this message.");
+        }
+
         protected override void ProcessRecord()
         {
             const string particular = @"Software\ParticularSoftware";