This function adds the word draft to certain graphics.
add_draft(label = "DRAFT", size = 10, colour = "grey50", x = Inf,
y = -Inf, ...)
draft layer default to DRAFT
size of the annotation
color of the annotation default to grey50
numeric
x coordinate of the draft label
numeric
y coordinate of the draft label
extra parameters to geom text used to annotate the draft
ggplot2 annotation