fixes the dependency of labeller example on plyr in issue #3083 (#3087)

* fixes the dependency of labeller example on plyr in issue #3083

* adding the .Rd documentation component for labeller

* split into two assignments

Author: connorlewis

R/labeller.r

@@ -398,7 +398,9 @@ as_labeller <- function(x, default = label_value, multi_line = TRUE) {
 #'
 #' # In the following example, we rename the levels to the long form,
 #' # then apply a wrap labeller to the columns to prevent cropped text
-#' msleep$conservation2 <- revalue(msleep$conservation, conservation_status)
+#' idx <- match(msleep$conservation, names(conservation_status))
+#' msleep$conservation2 <- conservation_status[idx]
+#'
 #' p3 <- ggplot(msleep, aes(x = sleep_total, y = awake)) + geom_point()
 #' p3 +
 #'   facet_grid(vore ~ conservation2,