docs: update README.md

Signed-off-by: clavinjune <[email protected]>

Author: clavinjune

README.md

@@ -3,7 +3,8 @@
 ## Get Repository Info
 
 This repository support HTTPS and OCI:
-- [https://gopaytech.github.io/helm-charts]
+- [https://gopaytech.github.io/helm-charts](https://gopaytech.github.io/helm-charts)
+- [oci://ghcr.io/gopaytech/helm-charts/mtr-exporter](oci://ghcr.io/gopaytech/helm-charts/mtr-exporter)
 
 ```shell
 helm repo add gopaytech https://gopaytech.github.io/helm-charts