Explicitly included rootTopic parameter name

This is a bit silly, but in addition to adding to the intuition about the underlying route parameters, this prevents the aligned comments from being misaligned due to Visual Studio's (optional) parameter hints.

Author: JeremyCaney

OnTopic.AspNetCore.Mvc.Host/Program.cs

@@ -70,9 +70,11 @@
 app.MapImplicitAreaControllerRoute();                           // {area:exists}/{action=Index}
 app.MapDefaultAreaControllerRoute();                            // {area:exists}/{controller}/{action=Index}/{id?}
 app.MapTopicAreaRoute();                                        // {area:exists}/{**path}
+
+app.MapTopicErrors(rootTopic: "Error");                         // Error/{statusCode}
 app.MapDefaultControllerRoute();                                // {controller=Home}/{action=Index}/{id?}
-app.MapTopicRoute("Web");                              // Web/{**path}
-app.MapTopicRoute("Error");                            // Error/{**path}
+app.MapTopicRoute(rootTopic: "Web");                            // Web/{**path}
+app.MapTopicRoute(rootTopic: "Error");                          // Error/{**path}
 app.MapTopicSitemap();                                          // Sitemap
 app.MapTopicRedirect();                                         // Topic/{topicId}
 app.MapControllers();