position_raincloud: Create a cloud of randomly jittered points below a ridgeline plot
Description
This is a position adjustment specifically for geom_density_ridges() and related geoms. It
only jitters the points drawn by these geoms, if any. If no points are present, the plot
remains unchanged. The effect is similar to position_points_jitter(), only that by default the
points lie all underneath the baseline of each individual ridgeline.