Update cheatsheet.fr.md

10.temporary-m3p2/12.Fundamental-experiments-in-physics/16.young-double-slit-experiment/20.n2/cheatsheet.fr.md

@@ -8,6 +8,10 @@ lessons:
       slug: waves-in-fundamental-experiments-2
       name: PARADIGM-SHIFTS : From waves to Relativity and Quantum Physics
       order: 3
+    -
+      slug: duality-young-experiment-from-classical-to-quantic-mechanics
+      name: THEORIE-EXP : Double-fente d'Young et dualité onde-corpuscule
+      order: 2
 ---
 
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