mcr.microsoft.com "About" document requires updating about deprecation

[JustinGrote]

Summary of the new feature / enhancement

https://mcr.microsoft.com/en-us/artifact/mar/powershell/about

This needs to be updated to inform the community linking to the announcement and that they are currently unmaintained. That can change if a new forward direction is chosen.

Proposed technical implementation details (optional)

No response