Clarified how Raster and Image now relate
Clarified how Raster and Image now relate

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