Update Startup4.cs

aspnetcore/tutorials/web-api-help-pages-using-swagger/samples/2.0/TodoApi.Swashbuckle/Startup4.cs

@@ -56,8 +56,7 @@ namespace TodoApi
 
                 // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
                 // specifying the Swagger JSON endpoint.
-                // Protected by if (env.IsDevelopment())
-                app.UseSwaggerUI(c =>
+                app.UseSwaggerUI(c =>  // UseSwaggerUI is called only in Development.
                 {
                     c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
                 });