Fixed typo in map_data() documentation (#4278) (#4303)

Co-authored-by: Heath <heathgilham@gmail.com>

Author: heathgilham

R/fortify-map.r

@@ -66,13 +66,13 @@ fortify.map <- function(model, data, ...) {
 #' choro <- choro[order(choro$order), ]
 #' ggplot(choro, aes(long, lat)) +
 #'   geom_polygon(aes(group = group, fill = assault)) +
-#'   coord_map("albers",  at0 = 45.5, lat1 = 29.5)
+#'   coord_map("albers",  lat0 = 45.5, lat1 = 29.5)
 #' }
 #'
 #' if (require("maps")) {
 #' ggplot(choro, aes(long, lat)) +
 #'   geom_polygon(aes(group = group, fill = assault / murder)) +
-#'   coord_map("albers",  at0 = 45.5, lat1 = 29.5)
+#'   coord_map("albers",  lat0 = 45.5, lat1 = 29.5)
 #' }
 map_data <- function(map, region = ".", exact = FALSE, ...) {
   try_require("maps", "map_data")