12.3 ggtext: HTML formatting in ggplot

Use HTML to format text and include images in ggplot axes labels (element_markdown) and point labels (geom_richtext).

• https://wilkelab.org/ggtext/
• With country flags, downloaded from wikipedia https://www.r-bloggers.com/2019/08/ggtext-for-images-as-x-axis-labels/#google_vignette
• Images below x-axis labels. https://stackoverflow.com/questions/67491715/adding-images-below-x-axis-labels-in-ggplot2
• Images for y-axis labels. https://stackoverflow.com/questions/68747698/r-ggplot2-images-as-y-axis-labels