Updates to workload config command

src/Cli/dotnet/commands/dotnet-workload/config/LocalizableStrings.resx

@@ -118,6 +118,10 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="CommandDescription" xml:space="preserve">
-    <value>Modify or display workload configuration values.</value>
+    <value>Modify or display workload configuration values.
+To display a value, specify the corresponding command-line option without providing a value.  For example: "dotnet workload config --update-mode"</value>
+  </data>
+  <data name="UpdateModeDescription" xml:space="preserve">
+    <value>Controls whether updates should look for workload sets or the latest version of each individual manifest.</value>
   </data>
 </root>

src/Cli/dotnet/commands/dotnet-workload/config/WorkloadConfigCommand.cs

@@ -80,13 +80,13 @@ public override int Execute()
                 }
                 else
                 {
-                    Reporter.WriteLine($"Invalid update mode: {_updateMode}");
-                    return 1;
+                    //  This should not be hit, as parser sets the accepted values and should error before getting here if the value is not valid
+                    throw new InvalidOperationException($"Invalid update mode: {_updateMode}");
                 }
             }
             else
             {
-                Reporter.WriteLine("No update mode specified");
+                _parseResult.ShowHelp();
             }
 
             return 0;

src/Cli/dotnet/commands/dotnet-workload/config/WorkloadConfigCommandParser.cs

@@ -15,7 +15,7 @@ internal static class WorkloadConfigCommandParser
 
         public static readonly CliOption<string> UpdateMode = new("--update-mode")
         {
-            Description = "Set the update mode for the workload manifest",
+            Description = LocalizableStrings.UpdateModeDescription,
             //Hidden = true,
             Arity = ArgumentArity.ZeroOrOne
         };