Update status

To be consistent with the rest of the FirebaseExtended GitHub org

Author: jhuleatt

README.md

@@ -127,6 +127,8 @@ The time the deployed preview urls expire
 
 A single URL that was deployed to
 
----
+## Status
 
-This GitHub Action is not an officially supported Google product
+![Status: Experimental](https://img.shields.io/badge/Status-Experimental-blue)
+
+This repository is maintained by Googlers but is not a supported Firebase product. Issues here are answered by maintainers and other community members on GitHub on a best-effort basis.