Add request processing pipeline diagrams to middleware doc (#17623)

* Add request processing pipeline diagrams to middleware doc

* minor edit

* minor edits

* React to feedback

Author: scottaddie

aspnetcore/fundamentals/middleware/index.md

@@ -5,7 +5,7 @@ description: Learn about ASP.NET Core middleware and the request pipeline.
 monikerRange: '>= aspnetcore-2.1'
 ms.author: riande
 ms.custom: mvc
-ms.date: 02/02/2020
+ms.date: 04/06/2020
 uid: fundamentals/middleware/index
 ---
 # ASP.NET Core Middleware
@@ -62,9 +62,17 @@ In the preceding example, the `Run` delegate writes `"Hello from 2nd delegate."`
 
 ## Middleware order
 
+The following diagram shows the complete request processing pipeline for ASP.NET Core MVC and Razor Pages apps. You can see how, in a typical app, existing middlewares are ordered and where custom middlewares are added. You have full control over how to reorder existing middlewares or inject new custom middlewares as necessary for your scenarios.
+
+![ASP.NET Core middleware pipeline](index/_static/middleware-pipeline.svg)
+
+The **Endpoint** middleware in the preceding diagram executes the filter pipeline for the corresponding app type—MVC or Razor Pages.
+
+![ASP.NET Core filter pipeline](index/_static/mvc-endpoint.svg)
+
 The order that middleware components are added in the `Startup.Configure` method defines the order in which the middleware components are invoked on requests and the reverse order for the response. The order is **critical** for security, performance, and functionality.
 
-The following `Startup.Configure` method adds security related middleware components in the recommended order:
+The following `Startup.Configure` method adds security-related middleware components in the recommended order:
 
 [!code-csharp[](index/snapshot/StartupAll3.cs?name=snippet)]