doc: Add known issue about peer probe with op-version

Change-Id: I152e5b63329540b65a86bc75f0a0c3a831761aaa
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/5450
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Vijay Bellur <vbellur@redhat.com>