Generic Host clean up (#17783)

* Generic Host clean up

* Generic Host clean up

* Generic Host clean up

Author: Rick-Anderson

aspnetcore/fundamentals/host/generic-host.md

@@ -12,9 +12,9 @@ uid: fundamentals/host/generic-host
 
 ::: moniker range=">= aspnetcore-3.0 <= aspnetcore-3.1"
 
-This article introduces the .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>) and provides guidance on how to use it.
+The ASP.NET Core templates create a .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>).
 
-## What's a host?
+## Host definition
 
 A *host* is an object that encapsulates an app's resources, such as:
 
@@ -27,16 +27,33 @@ When a host starts, it calls `IHostedService.StartAsync` on each implementation
 
 The main reason for including all of the app's interdependent resources in one object is lifetime management: control over app startup and graceful shutdown.
 
-In versions of ASP.NET Core earlier than 3.0, the [Web Host](xref:fundamentals/host/web-host) is used for HTTP workloads. The Web Host is no longer recommended for web apps and remains available only for backward compatibility.
-
 ## Set up a host
 
 The host is typically configured, built, and run by code in the `Program` class. The `Main` method:
 
 * Calls a `CreateHostBuilder` method to create and configure a builder object.
 * Calls `Build` and `Run` methods on the builder object.
 
-Here's *Program.cs* code for a non-HTTP workload, with a single `IHostedService` implementation added to the DI container. 
+The ASP.NET Core web templates generate the following code to create a host:
+
+```csharp
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        CreateHostBuilder(args).Build().Run();
+    }
+
+    public static IHostBuilder CreateHostBuilder(string[] args) =>
+        Host.CreateDefaultBuilder(args)
+            .ConfigureWebHostDefaults(webBuilder =>
+            {
+                webBuilder.UseStartup<Startup>();
+            });
+}
+```
+
+The following code creates a non-HTTP workload with a `IHostedService` implementation added to the DI container.
 
 ```csharp
 public class Program
@@ -970,9 +987,9 @@ public class MyClass
 
 ::: moniker range=">= aspnetcore-5.0"
 
-This article introduces the .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>) and provides guidance on how to use it.
+The ASP.NET Core templates create a .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>).
 
-## What's a host?
+## Host definition
 
 A *host* is an object that encapsulates an app's resources, such as:
 
@@ -985,16 +1002,33 @@ When a host starts, it calls `IHostedService.StartAsync` on each implementation
 
 The main reason for including all of the app's interdependent resources in one object is lifetime management: control over app startup and graceful shutdown.
 
-In versions of ASP.NET Core earlier than 3.0, the [Web Host](xref:fundamentals/host/web-host) is used for HTTP workloads. The Web Host is no longer recommended for web apps and remains available only for backward compatibility.
-
 ## Set up a host
 
 The host is typically configured, built, and run by code in the `Program` class. The `Main` method:
 
 * Calls a `CreateHostBuilder` method to create and configure a builder object.
 * Calls `Build` and `Run` methods on the builder object.
 
-Here's *Program.cs* code for a non-HTTP workload, with a single `IHostedService` implementation added to the DI container. 
+The ASP.NET Core web templates generate the following code to create a host:
+
+```csharp
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        CreateHostBuilder(args).Build().Run();
+    }
+
+    public static IHostBuilder CreateHostBuilder(string[] args) =>
+        Host.CreateDefaultBuilder(args)
+            .ConfigureWebHostDefaults(webBuilder =>
+            {
+                webBuilder.UseStartup<Startup>();
+            });
+}
+```
+
+The following code creates a non-HTTP workload with a `IHostedService` implementation added to the DI container.
 
 ```csharp
 public class Program