doc: mention encryption is not supported for static PVC

Also add a generic warning under both RBD and CephFS sections
that features requiring ceph-csi to manage the volume lifecycle
are not supported for static PVC.

Closes: #6209
Signed-off-by: Praveen M <m.praveen@ibm.com>

Author: iPraveenParihar

docs/static-pvc.md

@@ -21,11 +21,15 @@ existing RBD image or CephFS volume.
 
 > [!warning]
 > static PVC can be created, deleted, mounted and unmounted but
-currently ceph-csi doesn't support other operations like snapshot,clone,
-resize, etc for static PVC
+currently ceph-csi doesn't support other operations like snapshot, clone,
+resize, encryption etc for static PVC
 
 ## RBD static PVC
 
+> [!warning]
+> Features that require ceph-csi to manage the volume lifecycle are not
+supported for static RBD PVC
+
 RBD images created manually can be mounted and unmounted to an app, below step
 shows how to create a RBD image, static PV, static PVC
 
@@ -200,6 +204,10 @@ manually delete the RBD image if required
 
 ## CephFS static PVC
 
+> [!warning]
+> Features that require ceph-csi to manage the volume lifecycle are not
+supported for static CephFS PVC
+
 CephFS subvolume or volume created manually can be mounted and unmounted
 to an app, below steps show how to create a CephFS subvolume or volume,
 static PV and static PVC.