modified docstring for mnw1
modified docstring for mnw1

this package appears to be old-style so I didn't spend much time on complete dcostrings

jentjr/flopy,brclark-usgs/flopy,aleaf/flopy,jentjr/flopy,aleaf/flopy,brclark-usgs/flopy,bdestombe/flopy-1,mrustl/flopy