Add example showing how to use the fill argument in stat_function() (#4420)

Author: Bisaloo

R/geom-function.R

@@ -32,6 +32,8 @@
 #'
 #' base + stat_function(fun = dnorm, geom = "point", n = 20)
 #'
+#' base + stat_function(fun = dnorm, geom = "polygon", color = "blue", fill = "blue", alpha = 0.5)
+#'
 #' base + geom_function(fun = dnorm, n = 20)
 #'
 #' # Two functions on the same plot