fix to_netcdf docstring typo (#4021)
fix to_netcdf docstring typo (#4021)


pydata/xarray,pydata/xarray,markelg/xray,shoyer/xarray,pydata/xarray,markelg/xray,shoyer/xarray,jhamman/xarray,xray/xray,jhamman/xarray,markelg/xray,jhamman/xarray