Update textbook.fr.md

00.brainstorming-pedagogical-teams/45.synthesis-structuring/40.electromagnetism/40.n4/10.brainstorming/20.en/textbook.fr.md

@@ -3,10 +3,13 @@ title: Brainstorming to structure an "Electromagnetism" theme
 published: true
 routable: true
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+---
+
+<!----------------------------------------
 lessons:
     - slug: brainstorming-234-electromagnetism
       order: 3
----
+------------------------------------------>
 
 #### Brainstorming to structure an "Electromagnetism" theme: level 4