Update cheatsheet.en.md

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

@@ -124,15 +124,15 @@ It’s called the *Kelvin wake*."
 _Sometimes, all it takes is moving at the right speed for the world to draw you a path._
 
 
-!!! <details markdown=1><summary><strong>The Physicist's Eye</strong></summary>
-
-A **wave** is a **disturbance in a medium created by a source** that **propagates in all directions** at the **speed of the wave**.
-
-----------
-
-**The source is stationary in the medium**
-
-![](https://m3p2.com/fr/temporary_ins/waves/n2/overview/waves-doppler-immob_1ok_L900.gif)
+! <details markdown=1><summary><strong>The Physicist's Eye</strong></summary>
+! 
+! A **wave** is a **disturbance in a medium created by a source** that **propagates in all directions** at the **speed of the wave**.
+! 
+! ----------
+! 
+! **The source is stationary in the medium**
+! 
+! ![](https://m3p2.com/fr/temporary_ins/waves/n2/overview/waves-doppler-immob_1ok_L900.gif)
 !
 ! * Just as your voice disturbs the air and spreads in all directions,
 ! the duck disturbs the water, and circular ripples propagate across the water's surface, all centered on the duck.