typo

README.md

@@ -32,14 +32,14 @@ python seedling_tray.py
 
 ### parametric_box
 Parameterized rectangular box with a clip in lid.  
-To generate the box and lid STL file:
+To generate the box and lid STL files:
 ```bash
 python parametric_box.py
 ```
 
 ### pill_container
 Parameterized pill containers with a sliding lid.  
-To generate the box and lid STL file:
+To generate the box and lid STL files:
 ```bash
 python pill_container.py
 ```