Updated the class docstring for GridColumns
Updated the class docstring for GridColumns

vascotenner/holoviews,ioam/holoviews,basnijholt/holoviews,vascotenner/holoviews,basnijholt/holoviews,basnijholt/holoviews,ioam/holoviews,vascotenner/holoviews,ioam/holoviews