Fix potentially confusing footnote, closes #1516

joins.qmd

@@ -220,7 +220,7 @@ flights2
 ```
 
 There are four types of mutating join, but there's one that you'll use almost all of the time: `left_join()`.
-It's special because the output will always have the same rows as `x`[^joins-2].
+It's special because the output will always have the same rows as `x`, the data frame you're joining to[^joins-2].
 The primary use of `left_join()` is to add in additional metadata.
 For example, we can use `left_join()` to add the full airline name to the `flights2` data: