Update transform.Rmd

Corrected a filter in an example.

transform.Rmd

@@ -598,7 +598,7 @@ delays <- flights %>%
     dist = mean(distance, na.rm = TRUE),
     delay = mean(arr_delay, na.rm = TRUE)
   ) %>% 
-  filter(delay, count > 20, dest != "HNL")
+  filter(count > 20, dest != "HNL")
 ```
 
 This focuses on the transformations, not what's being transformed, which makes the code easier to read. You can read it as a series of imperative statements: group, then summarise, then filter. As suggested by this reading, a good way to pronounce `%>%` when reading code is "then".