Add callout to attract users

index.md

@@ -4,3 +4,10 @@ site: sandpaper::sandpaper_site
 
 This is the GPU programming lesson.
 
+::: callout
+## Do you want to teach this lesson?
+Do you want to teach GPU programming? This material is open-source and freely available. 
+Are you planning on using our material in your teaching? 
+Send us an email at [email protected]. 
+We would love to help you prepare to teach the lesson and receive feedback on how it could be further improved, based on your experience in the workshop.
+:::