Mark ophan pages as such, from https://documatt.com/sphinx-errors/1-document-isnt-included-in-any/#solution

richelbilderbeek · richelbilderbeek · commit e2e75f398d63 · 2026-03-31T12:48:08.000+02:00
diff --git a/docs/lesson_plans/20250425/README.md b/docs/lesson_plans/20250425/README.md
@@ -1,3 +1,4 @@
+(orphan)=
 # Lesson plan 2025-04-25 by Richel
 
 Here is the current schedule:
diff --git a/docs/lesson_plans/20251128/README.md b/docs/lesson_plans/20251128/README.md
@@ -1,3 +1,4 @@
+(orphan)=
 # Lesson plan
 
 - Date: 2025-12-28
diff --git a/docs/lesson_plans/20260422/README.md b/docs/lesson_plans/20260422/README.md
@@ -1,3 +1,4 @@
+(orphan)=
 # Lesson plan 2026-04-22 by Richel
 
 - Day 2, first two hours
diff --git a/docs/lesson_plans/20260423/README.md b/docs/lesson_plans/20260423/README.md
@@ -1,3 +1,4 @@
+(orphan)=
 # Lesson plan 2026-04-23 by Richel
 
 - 09:00-10:00 Matplotlib
