Add deprecation note:

Author: jacobweinstock

README.md

@@ -1,3 +1,8 @@
+> [!IMPORTANT]  
+> The Hegel repo has been deprecated. All functionality has been moved to https://github.com/tinkerbell/tinkerbell.
+> For more details, see the roadmap issue [#41](https://github.com/tinkerbell/roadmap/issues/41).
+> This repository is scheduled for archive by the end of 2025.
+
 # Hegel
 
 [![Build status](https://img.shields.io/github/actions/workflow/status/tinkerbell/hegel/ci.yaml?branch=main)](https://img.shields.io/github/actions/workflow/status/tinkerbell/hegel/ci.yaml?branch=main) 
@@ -117,4 +122,4 @@ enables integration with other tooling.
 [semver]: https://semver.org/
 [equinix-metadata]: https://deploy.equinix.com/developers/docs/metal/server-metadata/metadata/
 [hub]: https://github.com/tinkerbell/hub
-[ec2-im]: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html
+[ec2-im]: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-categories.html