Point extensions docs to .NET content (#20100)

* Point extensions docs to .NET content

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* Update aspnetcore/fundamentals/host/generic-host.md

Co-authored-by: Tom Dykstra <tdykstra@microsoft.com>

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Co-authored-by: Tom Dykstra <tdykstra@microsoft.com>

Author: Rick-Anderson

aspnetcore/fundamentals/configuration/index.md

@@ -26,6 +26,8 @@ Configuration in ASP.NET Core is performed using one or more [configuration prov
 * Directory files
 * In-memory .NET objects
 
+This topic provides information on configuration in ASP.NET Core. For information on using configuration in console apps, see [.NET Configuration](/dotnet/core/extensions/configuration).
+
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/configuration/index/samples) ([how to download](xref:index#how-to-download-a-sample))
 
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aspnetcore/fundamentals/configuration/options.md

@@ -22,6 +22,8 @@ The options pattern uses classes to provide strongly typed access to groups of r
 
 Options also provide a mechanism to validate configuration data. For more information, see the [Options validation](#options-validation) section.
 
+This topic provides information on the options pattern in ASP.NET Core. For information on using the options pattern in console apps, see [Options pattern in .NET](/dotnet/core/extensions/options).
+
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/configuration/options/samples) ([how to download](xref:index#how-to-download-a-sample))
 
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aspnetcore/fundamentals/dependency-injection.md

@@ -21,6 +21,8 @@ For more information specific to dependency injection within MVC controllers, se
 
 For more information on dependency injection of options, see <xref:fundamentals/configuration/options>.
 
+This topic provides information on dependency injection in ASP.NET Core. For information on using dependency injection  in console apps, see [Dependency injection in .NET](/dotnet/core/extensions/dependency-injection).
+
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/dependency-injection/samples) ([how to download](xref:index#how-to-download-a-sample))
 
 ## Overview of dependency injection

aspnetcore/fundamentals/host/generic-host.md

@@ -1,20 +1,22 @@
 ---
-title: .NET Generic Host
+title: .NET Generic Host in ASP.NET Core
 author: rick-anderson
-description: Learn about the .NET Core Generic Host, which is responsible for app startup and lifetime management.
+description: Use .NET Core Generic Host in ASP.NET Core apps.  Generic Host is responsible for app startup and lifetime management.
 monikerRange: '>= aspnetcore-2.1'
 ms.author: riande
 ms.custom: mvc
 ms.date: 4/17/2020
 no-loc: ["ASP.NET Core Identity", cookie, Cookie, Blazor, "Blazor Server", "Blazor WebAssembly", "Identity", "Let's Encrypt", Razor, SignalR]
 uid: fundamentals/host/generic-host
 ---
-# .NET Generic Host
+# .NET Generic Host in ASP.NET Core
 
 ::: moniker range=">= aspnetcore-5.0"
 
 The ASP.NET Core templates create a .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>).
 
+This topic provides information on using .NET Generic Host in ASP.NET Core. For information on using .NET Generic Host in console apps, see [.NET Generic Host](/dotnet/core/extensions/generic-host).
+
 ## Host definition
 
 A *host* is an object that encapsulates an app's resources, such as:
@@ -514,6 +516,8 @@ public class Program
 
 The ASP.NET Core templates create a .NET Core Generic Host (<xref:Microsoft.Extensions.Hosting.HostBuilder>).
 
+This topic provides information on using .NET Generic Host in ASP.NET Core. For information on using .NET Generic Host in console apps, see [.NET Generic Host](/dotnet/core/extensions/generic-host).
+
 ## Host definition
 
 A *host* is an object that encapsulates an app's resources, such as:

aspnetcore/fundamentals/logging/index.md

@@ -19,6 +19,8 @@ By [Kirk Larkin](https://twitter.com/serpent5), [Juergen Gutsch](https://github.
 
 Most of the code examples shown in this article are from ASP.NET Core apps. The logging-specific parts of these code snippets apply to any .NET Core app that uses the [Generic Host](xref:fundamentals/host/generic-host). The ASP.NET Core web app templates use the Generic Host.
 
+This topic provides information on logging in ASP.NET Core. For information on logging in console apps, see [.NET Logging](/dotnet/core/extensions/logging).
+
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/logging/index/samples/3.x) ([how to download](xref:index#how-to-download-a-sample))
 
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