Fix minor plaintext typos (#1085)

Co-authored-by: Betul Turkoglu <79486373+betulturkoglu@users.noreply.github.com>

data-visualize.qmd

@@ -610,7 +610,7 @@ Many geoms, like `geom_smooth()`, use a single geometric object to display multi
 For these geoms, you can set the `group` aesthetic to a categorical variable to draw multiple objects.
 ggplot2 will draw a separate object for each unique value of the grouping variable.
 In practice, ggplot2 will automatically group the data for these geoms whenever you map an aesthetic to a discrete variable (as in the `linetype` example).
-It is convenient to rely on this feature because the group aesthetic by itself does not add a legend or distinguishing features to the geoms.
+It is convenient to rely on this feature because the `group` aesthetic by itself does not add a legend or distinguishing features to the geoms.
 
 ```{r}
 #| layout-ncol: 3