Document WithCommand return-value payloads (Text/Json/Markdown) for Aspire 13.3

src/frontend/src/content/docs/dashboard/explore.mdx

@@ -579,13 +579,15 @@ Selecting **View response** opens the text visualizer with the command's result
 
 <Image src={notificationCenterResponse} alt="Aspire dashboard text visualizer showing a command response opened from the notification center." />
 
+Markdown command results render as formatted Markdown in the text visualizer (for example, headings and tables), not as raw markdown source.
+
 The unread count resets when you open the notification center. To clear all notifications, select the **Dismiss all** button in the dialog.
 
 <Aside type="tip">
 Notifications are capped at 100 entries. When the limit is reached, the oldest notifications are removed automatically.
 </Aside>
 
-For information on returning messages from custom commands, see [Custom resource commands](/fundamentals/custom-resource-commands/).
+For information on returning command result payloads from custom commands, see [Custom resource commands](/fundamentals/custom-resource-commands/).
 
 ## Settings dialog
 

src/frontend/src/content/docs/fundamentals/custom-resource-commands.mdx

@@ -676,7 +676,7 @@ return { success: false, message: err instanceof Error ? err.message : String(er
 </TabItem>
 </Tabs>
 
-## Return structured output from a command
+## Returning a result from a command
 
 Resource commands can return a structured payload — plain text, JSON, or Markdown — alongside the success/failure signal. The payload flows automatically through the entire Aspire pipeline:
 
@@ -826,6 +826,47 @@ await builder.build().run();
 </TabItem>
 </Tabs>
 
+### Return Markdown
+
+When a command needs rich output (for example headings, tables, and lists), return `CommandResultData` with `Format = CommandResultFormat.Markdown`:
+
+```csharp title="C# — AppHost.cs"
+builder
+    .AddProject<Projects.MyService>("myservice")
+    .WithCommand(
+        name: "migrate-database",
+        displayName: "Migrate Database",
+        executeCommand: _ =>
+        {
+            var markdown = """
+                # ⚙️ Database Migration Summary
+
+                | Table      | Result                     |
+                |------------|----------------------------|
+                | Customers  | ✅ 1,200 rows              |
+                | Products   | ✅ 850 rows                |
+                | Orders     | ✅ 3,400 rows              |
+                | OrderItems | ✅ 8,750 rows              |
+                | Categories | ✅ 45 rows                 |
+                | Reviews    | ❌ FK constraint violation |
+                | Inventory  | ✅ 850 rows                |
+                | Shipping   | ✅ 3,400 rows              |
+                | Payments   | ❌ Timeout after 30s       |
+                | Coupons    | ✅ 120 rows                |
+
+                **Summary:** 8 of 10 tables migrated successfully. 2 tables failed.
+                """;
+
+            return Task.FromResult(CommandResults.Success(
+                "Database migrated.",
+                new CommandResultData
+                {
+                    Value = markdown,
+                    Format = CommandResultFormat.Markdown,
+                }));
+        });
+```
+
 ### Choose a result format
 
 `CommandResultFormat` has three values:

src/frontend/src/content/docs/whats-new/aspire-13-3.mdx

@@ -521,7 +521,7 @@ await builder.build().run();
 
 ### Resource commands return structured results
 
-Custom resource commands can now return an `ExecuteCommandResult` with a structured `Message` payload that the dashboard renders in the notification center. The new `Logger` property on `ExecuteCommandContext` lets command implementations log directly to the resource's log stream.
+Custom resource commands can now return an `ExecuteCommandResult` with structured `Data` payloads (`Text`, `Json`, or `Markdown`) that the dashboard renders from the notification center's **View response** action. The `CommandResults.Success(string, CommandResultData)` overload also makes it easy to return markdown tables and other rich output from a command. The new `Logger` property on `ExecuteCommandContext` lets command implementations log directly to the resource's log stream.
 
 <Tabs syncKey='aspire-lang'>
 <TabItem id='csharp' label='AppHost.cs'>