Update README

README.md

@@ -10,8 +10,9 @@ Like WorldEdit's `//stack`, but
 - supports more directions, in particular ones used in diagonal building orientations
 - has a flag for expanding the selection to cover the whole stacked area
 
-Usage: `//rstack [-e] [direction] [count] [spacing]`
+Usage: `//rstack [-e] [-w] [direction] [count] [spacing]`
 - `-e`: when specified, the selection is expanded
+- `-w` ("with air"): when specified, **stacked copies may not overlap** (corresponds to omitting `-a` from WorldEdit commands)
 - `direction`: the usual WorldEdit directions. Additionally, `u` or `d` may be appended to
 most directions to get a diagonal (in the y-axis) direction. Defaults to `me`
 (whatever direction you're looking at)