Update textbook.en.md

00.brainstorming-pedagogical-teams/45.synthesis-structuring/electromagnetism/n2/textbook.en.md

@@ -4,8 +4,10 @@ published: true
 routable: true
 visible: false
 lessons:
-    - slug: brainstorming-n1234-electromagnetism
+    - slug: brainstorming-123-electromagnetism
       order: 2
+    - slug: brainstorming-234-electromagnetism
+      order: 1
 ---
 
 #### Brainstorming to structure a theme "Electromagnetism" : level 2