Update containers for preview 7 (#9995)

* Update containers for preview 7

* Add dnx feature notes

---------

Co-authored-by: Logan Bussell <[email protected]>

Author: jamesmontemagno

release-notes/10.0/preview/preview7/containers.md

@@ -2,12 +2,25 @@
 
 Here's a summary of what's new in Containers in this preview release:
 
-- [Feature](#feature)
+- [`dnx` is now on the `PATH` in SDK images](#dnx-is-now-on-the-path-in-sdk-images)
 
 Containers updates in .NET 10:
 
 - [What's new in .NET 10](https://learn.microsoft.com/dotnet/core/whats-new/dotnet-10/overview) documentation
 
-## Feature
+## `dnx` is now on the `PATH` in SDK images
 
-Something about the feature
+`dnx` is now available directly from .NET 10 SDK container images. See [One-shot tool execution](../preview6/sdk.md#one-shot-tool-execution) for more details about `dnx`.
+
+To run a .NET tool using `dnx` in your Dockerfile build, you can use the following syntax:
+
+```Dockerfile
+FROM mcr.microsoft.com/dotnet/sdk:10.0-preview
+RUN dnx --yes <packageId> [<commandArguments>...]
+```
+
+To use `dnx` from the .NET SDK image directly from the command line, you can use the following Docker command:
+
+```console
+docker run --rm mcr.microsoft.com/dotnet/sdk:10.0-preview dnx --yes <packageId> [<commandArguments>...]
+```