Add example for Problem result in Minimal APIs

Author: timdeschryver

aspnetcore/fundamentals/minimal-apis/9.0-samples/Snippets/Program.cs

@@ -46,7 +46,14 @@ public static void Main(string[] args)
         // <snippet_10>
         app.MapGet("/download", () => Results.File("myfile.text"));
         // </snippet_10>
-
+        // <snippet_12>
+        app.MapGet("/problem", () =>
+        {
+            var extensions = new List<KeyValuePair<string, object?>> { new("test", "value") };
+            return TypedResults.Problem("This is an error with extensions", 
+                                                        extensions: extensions);
+        });
+        // </snippet_12>
         app.Run();
     }
     // <snippet_11>

aspnetcore/fundamentals/minimal-apis/responses.md

@@ -140,12 +140,20 @@ The following sections demonstrate the usage of the common result helpers.
 
 :::code language="csharp" source="~/fundamentals/minimal-apis/9.0-samples/Snippets/Program.cs" id="snippet_06":::
 
+:::moniker range=">= aspnetcore-9.0"
+
 #### Internal Server Error
 
 :::code language="csharp" source="~/fundamentals/minimal-apis/9.0-samples/Snippets/Program.cs" id="snippet_07":::
 
 The preceding example returns a 500 status code.
 
+#### Problem and ValidationProblem
+
+:::code language="csharp" source="~/fundamentals/minimal-apis/9.0-samples/Snippets/Program.cs" id="snippet_12":::
+
+:::moniker-end
+
 #### Text
 
 :::code language="csharp" source="~/fundamentals/minimal-apis/9.0-samples/Snippets/Program.cs" id="snippet_08":::