`prepare_chart` to be renamed to `prepareChart` in the Cookbook vignettes

[raheems]

Example 13 on this page https://cran.r-project.org/web/packages/safetyGraphics/vignettes/Cookbook.html need a minor fix in

qtOutliers<-prepare_chart(read_yaml('https://raw.githubusercontent.com/SafetyGraphics/safetyCharts/dev/inst/config/safetyOutlierExplorer.yaml') )

prepare_chart to be renamed to prepareChart

So it looks like

qtOutliers<-prepareChart(read_yaml('https://raw.githubusercontent.com/SafetyGraphics/safetyCharts/dev/inst/config/safetyOutlierExplorer.yaml') )