Update xcdat/spatial.py

Co-authored-by: Stephen Po-Chedley <pochedley@gmail.com>

Author: tomvothecoder

xcdat/spatial.py

@@ -77,7 +77,7 @@ def average(
     ) -> xr.Dataset:
         """
         Calculates the weighted spatial and/or vertical average for a
-        rectilinear grid over an optionally specified regional and/or vertical
+        rectilinear grid for an optionally specified regional and/or vertical
         domain.
 
         Operations include: