Note no office hours call on April 21

Author: schoen

docs/office-hours.md

@@ -18,6 +18,7 @@ You can also see all public Simplicity-related events in the public calendar:
 ## Upcoming topics
 
 * April 14, 2026: **Lending contract demo** Come see a demo of the [simplicity-lending](https://github.com/BlockstreamResearch/simplicity-lending) contract developed by our colleagues and learn about on-chain collateralized lending applications with Simplicity.
+* April 21, 2026: **Call is canceled** and will resume on April 28.
 
 ## Prior Office Hours session recordings