doc: Update README with Helm chart versioning info

Clarified versioning for Helm chart releases.

Author: andyzhangx

charts/README.md

@@ -11,6 +11,8 @@
     - `--set linux.kubelet="/var/snap/microk8s/common/var/lib/kubelet"` - sets correct path to microk8s kubelet even though a user has a folder link to it.
 
 ### install a specific version
+> [!IMPORTANT]  
+> Starting from version `1.18.0`, the prefix `v` is removed from hlem chart release so they are in line with [semver](https://semver.org). Therefore, when upgrading, refer to version `1.18.0` instead of `v1.18.0`.
 
 ```console
 helm repo add csi-driver-smb https://raw.githubusercontent.com/kubernetes-csi/csi-driver-smb/master/charts