Fix typo in function

Using wrong zoom_level for water_z10

layers/water/water.sql

@@ -151,7 +151,7 @@ RETURNS TABLE(geometry geometry, class text) AS $$
         SELECT * FROM water_z9 WHERE zoom_level = 9
         UNION ALL
         -- etldoc: water_z9 ->  layer_water:z10                   
-        SELECT * FROM water_z9 WHERE zoom_level = 10
+        SELECT * FROM water_z10 WHERE zoom_level = 10
         UNION ALL
         -- etldoc: water_z11 ->  layer_water:z11        
         SELECT * FROM water_z11 WHERE zoom_level = 11