Update textbook.en.md

00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/42.relativistic-mechanics/20.n2/10.main/textbook.en.md

@@ -6,6 +6,10 @@ visible: false
 lessons:
     - slug: relativity-linear-2
       order: 1
+    - slug: relativity-123-main-panorama
+      order: 2
+    - slug: relativity-234-main-panorama
+      order: 1
 ---
 
 Les relativités niveau 2 : main