chore: update readme for archiving (#109)

Resolve: #108
Signed-off-by: Lixia (Sylvia) Lei <[email protected]>

README.md

@@ -12,9 +12,9 @@
 `oras-credentials-go` is a credential management library designed for [`oras-go`](https://github.com/oras-project/oras-go). It supports reading, saving, and removing credentials from Docker configuration files and external credential stores that follow the [Docker credential helper protocol](https://docs.docker.com/engine/reference/commandline/login/#credential-helper-protocol).
 
 > [!IMPORTANT]
+> **This repository has been archived and is no longer maintained.**
+> 
 > The APIs previously located in this library have been moved to [`oras-go`](https://github.com/oras-project/oras-go). As a result, these APIs are now deprecated and users should use [the packages](https://pkg.go.dev/oras.land/oras-go/v2/registry/remote/credentials) in `oras-go` instead.
->
-> This repository will now be used for developing experimental features scoped to credentials management. If any of these features are deemed stable and applicable to `oras-go`, they may be moved there in the future.
 
 ## Versioning