Update vignettes/datatable-joins.Rmd

Co-authored-by: Michael Chirico <[email protected]>

Author: venom1204

vignettes/datatable-joins.Rmd

@@ -599,7 +599,7 @@ x[i, on = .(x_int >= i_int), .(i_int = i.i_int, x_int = x.x_int, lower, UPPER)]
 ```
 This ensures the output clearly distinguishes i_int (from i) and x_int (from x).
 
-If you want to exclude unmatched rows, you should use nomatch = NULL:
+If you want to exclude unmatched rows (an _inner join_), you should use nomatch = NULL:
 
 ```{r}
 x[i, on = .(x_int >= i_int), .(i_int = i.i_int, x_int = x.x_int, lower, UPPER), nomatch = NULL]