csi: add nodeExpandSecret KEP details

Ref#
KEP: kubernetes/enhancements#3173
Implementation: kubernetes/kubernetes#105963
Blog: kubernetes#33979

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

content/en/docs/concepts/storage/volumes.md

@@ -1228,6 +1228,18 @@ persistent volume:
   `NodePublishVolume` call. This field is optional, and may be empty if no
   secret is required. If the secret object contains more than one secret, all
   secrets are passed.
+`nodeExpandSecretRef`: A reference to the secret containing sensitive
+  information to pass to the CSI driver to complete the CSI
+  `NodeExpandVolume` call. This field is optional, and may be empty if no
+  secret is required. If the object contains more than one secret, all
+  secrets are passed.  When you have configured secret data for node-initiated
+  volume expansion, the kubelet passes that data via the `NodeExpandVolume()`
+  call to the CSI driver. In order to use the `nodeExpandSecretRef` field, your
+  cluster should be running Kubernetes version 1.25 or later and you must enable
+  the [feature gate](https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/)
+  named `CSINodeExpandSecret` for each kube-apiserver and for the kubelet on every
+  node. You must also be using a CSI driver that supports or requires secret data during
+  node-initiated storage resize operations.
 
 #### CSI raw block volume support
 

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -86,6 +86,7 @@ different Kubernetes components.
 | `CSIMigrationvSphere` | `false` | Beta | 1.19 | |
 | `CSIMigrationPortworx` | `false` | Alpha | 1.23 | |
 | `csiMigrationRBD` | `false` | Alpha | 1.23 | |
+| `CSINodeExpandSecret` | `false` | Alpha | 1.25 | |
 | `CSIVolumeHealth` | `false` | Alpha | 1.21 | |
 | `ContextualLogging` | `false` | Alpha | 1.24 | |
 | `CustomCPUCFSQuotaPeriod` | `false` | Alpha | 1.12 | |