doc: lift supported ceph version for snapshot/clone
doc: lift supported ceph version for snapshot/clone

snapshot and clone should be supported from octopus
15.2.4 instead of 15.2.3.

fixes #2732

Signed-off-by: Madhu Rajanna <60fbf37a92c2a0908e31296d18dadbec5a4dae17@gmail.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi