Release 0.4.0

Author: thekid

ChangeLog.md

@@ -3,6 +3,8 @@ AWS Lambda change log
 
 ## ?.?.? / ????-??-??
 
+## 0.4.0 / 2021-08-22
+
 * Renamed `xp lambda invoke` to `xp lambda test` to make clear we're
   not invoking the deployed lambda
   (@thekid)