Update cheatsheet.en.md

01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/01.geometrical-optics-general/01.geometrical-optics-validity/02.geometrical-optics-domain-of-validity-overview/cheatsheet.en.md

@@ -34,7 +34,8 @@ Finally, it allows us to understand how light can propagate in an optical fiber,
 
 <!--======================================
 Don't worry, the table below is well formatted on browsers.
-To translate into English, or to modify or complete then translate into en, es, fr
+To translate into English, or to modify or complete then translate into es and fr
+in the files cheatsheet.es.md and cheatsheet.es.md and cheatsheet.fr.md and 
 ========================================-->
 
  | |