doc: move release 3.4.0 to unsupported version
doc: move release 3.4.0 to unsupported version

As we have 3.6.0 release available now, moving 3.4.0
to unsupported version.

Signed-off-by: Humble Chirammal <dc8ba7e82a7df22725dedec9b10c7aaab9ec713f@redhat.com>

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