Add csi volume mode support note

docs/rancher/csi-driver.md

@@ -16,6 +16,9 @@ The Harvester Container Storage Interface (CSI) Driver provides a CSI interface
 - The Kubernetes cluster is built on top of Harvester virtual machines.
 - The Harvester virtual machines run as guest Kubernetes nodes are in the same namespace.
 
+!!! notes
+      Currently, the Harvester CSI driver only supports single-node read-write(RWO) volumes. Please follow the [issue #1992](https://github.com/harvester/harvester/issues/1992) for future multi-node `read-only`(ROX) and `read-write`(RWX) support.
+
 ### Deploying with Harvester RKE1 Node Driver
 
 - Select the external cloud provider option.