minor edit to vignette

vignettes/introduction.Rmd

@@ -168,7 +168,7 @@ As before, adding an argument for `metfun` to `show_trndseason()` will plot resu
 show_trndseason(mod, metfun = max, nsim = 100, doystr = 90, doyend = 180, justify = 'left', win = 5, ylab = 'Chl. change/yr, maximum')
 ```
 
-For additional visual clarity, the significant results in `show_sumtrndseason()` can be shown with different shapes indicating the direction of the trend using `usearrow = T`. This may be useful if significant trends are near the zero line.
+For additional visual clarity, the significant results in `show_trndseason()` can be shown with different shapes indicating the direction of the trend using `usearrow = T`. This may be useful if the direction of significant trends near the zero line are difficult to determine (not in the below example).
 
 ```{r, fig.height = 5, fig.width = 9, echo = T}
 show_trndseason(mod, metfun = max, nsim = 100, doystr = 90, doyend = 180, justify = 'left', win = 5, ylab = 'Chl. change/yr, maximum', usearrow = T)