Update index.mdx

Signed-off-by: Arya Gupta <arya.gupta99999@gmail.com>

Author: Arya-Gupta

content/pages/environment/index.mdx

@@ -99,7 +99,7 @@ Additional commands are found within the six menus: File, Edit, Sketch, Debug, T
   <dt>Preferences...</dt>
   <dd>
     Change some of the ways Processing works. (This item is located in the
-    Processing menu on Mac OS.)
+    Processing menu on macOS.)
   </dd>
   <dt>Quit</dt>
   <dd>