doc: include reference to NFS/ControllerModifyVolume in release-notes

Signed-off-by: Niels de Vos <ndevos@ibm.com>

Author: nixpanic

PendingReleaseNotes.md

@@ -8,5 +8,6 @@
    - refer design doc for more details - [here](https://github.com/ceph/ceph-csi/blob/devel/docs/design/proposals/userID-mapping.md)
 - cephfs-csi: fix mounting alternate filesystem when mounting by monitor lists [PR](https://github.com/ceph/ceph-csi/pull/5643)
 - rbd: add block volume stats support [PR](https://github.com/ceph/ceph-csi/pull/5799)
+- nfs: allow changing NFS-server through ControllerModifyVolume [PR](https://github.com/ceph/ceph-csi/pull/5829)
 
 ## NOTE