Remove obsolete nanoserver-arm32 references from samples documentation (#1953)

samples/aspnetapp/README.md

@@ -104,7 +104,7 @@ You can run these images in the same way as is done above, with Alpine.
 
 ## Build an image for ARM32 and ARM64
 
-By default, distro-specific .NET Core tags target x64, such as `3.1-alpine` or `3.1-nanoserver`. You need to use an architecture-specific tag if you want to target ARM. Note that .NET Core is only supported on Alpine on ARM64 and x64, and not ARM32.
+By default, distro-specific .NET Core tags target x64, such as `3.1-alpine` or `3.1-focal`. You need to use an architecture-specific tag if you want to target ARM. Note that .NET Core is only supported on Alpine on ARM64 and x64, and not ARM32.
 
 Note: Docker documentation sometimes refers to ARM32 as `armhf` and ARM64 as `aarch64`.
 
@@ -125,19 +125,6 @@ aspnetapp           debian-arm32        29a8bfa90a03        About a minute ago
 aspnetapp           alpine-arm64        8ec6bf841319        2 minutes ago        125MB
 ```
 
-You can do the same thing with Windows Nano Server, as follows:
-
-```console
-docker build --pull -t aspnetapp:nanoserver-arm32 -f Dockerfile.nanoserver-arm32 .
-```
-
-And `docker images` will show you the Nano Server image you've just built.
-
-```console
->docker images aspnetapp | findstr arm
-aspnetapp           nanoserver-arm32    8cad7f0499ca        23 seconds ago      283MB
-```
-
 You can build ARM32 and ARM64 images on ARM or x64 machines. It may be preferred to build on x64 to take advantage of higher performance, and the ability to take advantage of CI/CD services.
 
 You won't be able to run .NET Core ARM64 images on x64 machines. Docker relies on QEMU to run ARM64 images on X64, but [QEMU isn't supported by .NET Core](https://github.com/dotnet/coreclr/issues/12972). You must test and run .NET Core images on actual hardware for the given processor type.

samples/dotnetapp/README.md

@@ -137,7 +137,7 @@ FROM mcr.microsoft.com/dotnet/core/runtime:3.1-nanoserver-2004
 
 ## Build an image for ARM32 and ARM64
 
-By default, distro-specific .NET Core tags target x64, such as `3.1-alpine` or `3.1-nanoserver`. You need to use an architecture-specific tag if you want to target ARM. Note that for Alpine, .NET Core is only supported on ARM64 and x64, and not ARM32.
+By default, distro-specific .NET Core tags target x64, such as `3.1-alpine` or `3.1-focal`. You need to use an architecture-specific tag if you want to target ARM. Note that for Alpine, .NET Core is only supported on ARM64 and x64, and not ARM32.
 
 > Note: Docker documentation sometimes refers to ARM32 as `armhf` and ARM64 as `aarch64`.
 
@@ -162,13 +162,6 @@ dotnetapp           ubuntu-arm32        ea8ac73f8a72        20 hours ago
 dotnetapp           debian-arm32        4f6ade8318d4        20 hours ago        165MB
 ```
 
-You can do the same thing with Windows Nano Server, as follows:
-
-```console
-docker build --pull -t dotnetapp:nanoserver-arm32 -f Dockerfile.nanoserver-arm32 .
-docker images dotnetapp | findstr arm
-```
-
 You can build ARM32 and ARM64 images on x64 machines, but you will not be able to run them. Docker relies on QEMU for this scenario, which isn't supported by .NET Core. You must test and run .NET Core imges on actual hardware for the given processor type. A common pattern for this situation is building on x64, [pushing images to a registry](push-image-to-acr.md), and then pulling the image from an ARM device.
 
 ## Build an image optimized for startup performance