Update cheatsheet.en.md

12.temporary_ins/69.waves/10.n1/20.overview/cheatsheet.en.md

@@ -45,8 +45,25 @@ $`\def\PSclosed{\mathscr{S}_{\displaystyle\tiny\bigcirc}}`$
 
 <br>
 [multilingual version : EN , FR , ES](https://m3p2.com/polyglot/temporary_ins/waves/n1/overview)
+<br><br>
+
+Below, authors share **short tales** drawn from everyday life that **like magic uncover** *wave phenomena* hidden in our surroundings.**
+
+After each tale, you’ll be invited to:
+
+- *Observe or experiment* yourself,
+- *Decode through the physicist’s lens* the phenomenon,
+- *Spot the key terms* of wave vocabulary (highlighted for you).
+- *Conclude* with a maxim: a *law*, *concept*, or *fundamental property* of waves, stated simply.
+
+**Happy wave discovering :-)**
+
+
 <br>
 
+-----------------
+
+<br>
 
 #### The ripples pass, the leaf remains