Removed references to GridLayoutPlot and added LayoutPlot docstring
Removed references to GridLayoutPlot and added LayoutPlot docstring

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