[minor] Rename ".gridlines .baseline" to ".gridlines .zeroline" as it is more clear where it is applied and disambiguates from AreaPlot/BarPlot baseline
[minor] Rename ".gridlines .baseline" to ".gridlines .zeroline" as it is
more clear where it is applied and disambiguates from AreaPlot/BarPlot baseline

palantir/plottable,danmane/plottable,iobeam/plottable,jacqt/plottable,NextTuesday/plottable,onaio/plottable,softwords/plottable,alyssaq/plottable,gdseller/plottable,onaio/plottable,alyssaq/plottable,onaio/plottable,jacqt/plottable,iobeam/plottable,RobertoMalatesta/plottable,jacqt/plottable,gdseller/plottable,NextTuesday/plottable,danmane/plottable,palantir/plottable,palantir/plottable,palantir/plottable,alyssaq/plottable,softwords/plottable,iobeam/plottable,RobertoMalatesta/plottable,softwords/plottable,RobertoMalatesta/plottable,gdseller/plottable,NextTuesday/plottable,danmane/plottable