Update containers for RC 1 (#10050)

* Update containers for RC 1

* Clarify that the .NET 10 RC 1 release does not include new Container image features in the release notes.

Author: jongalloway

release-notes/10.0/preview/rc1/containers.md

@@ -1,8 +1,3 @@
 # Containers in .NET 10 RC 1 - Release Notes
 
-The following .NET 10 RC 1 release notes describe new features and changes in
-this release.
-
-## What's new features
-
-TBD
+This preview release does not contain new Container image features.