Added documentation for the Web MVC project

Author: jamesmcroft

docs/articles/features/web-mvc.md

@@ -5,3 +5,10 @@ title: Using the Web MVC package | MADE.NET
 
 # Using the Web MVC package
 
+The Web MVC library is a complementary extension package to ASP.NET Core MVC applications, providing additional helpers for building applications following the MVC pattern.
+
+## Returning an internal server error ObjectResult
+
+Out-of-the-box, the ASP.NET Core MVC packages don't contain a way of returning an internal server error (500) `ObjectResult` if an error occurs in your application.
+
+The `InternalServerErrorObjectResult` can be used to achieve this. It contains two constructors, one for providing the error, and another for providing a `ModelStateDictionary` model state containing validation errors.