Update README.rst
Update README.rst

Fixed syntax error with  # kthresher -p -k3 v which should be  # kthresher -p -k3 -v
rackerlabs/kthresher,rackerlabs/kthresher,Komish/kthresher,tonyskapunk/kthresher,delag/kthresher,tonyskapunk/kthresher,delag/kthresher,Komish/kthresher