Update documentation and changelog to mention plotlyVersion is now private

[Lectem]

It seems 44acbfd changed PlotlyViaCDNModule.plotlyVersion to be private, but this is not mentioned in the documentation nor the changelog.

PlotlyViaCDNModule.plotlyVersion = '1.47.4'; becomes PlotlyViaCDNModule.setPlotlyVersion('1.47.4');

[andrefarzat]

@Lectem you were right! Thanks a lot for letting us know 😸