gitflow-release-stash: 2.21.0

update release notes

Author: mayofaulkner

release_notes.md

@@ -1,5 +1,5 @@
 ## Release 2.21
-# Release Notes 2.21.0 2023-01-24
+# Release Notes 2.21.0 2023-02-14
 
 ### features
 - support for multiple task protocols within a session
@@ -17,6 +17,7 @@
 - fix region volume computation
 - vectorised swanson flatmap
 - brainbox trial ITI loader
+- vectorised atlas plots
 
 ## Release 2.20
 # Release Notes 2.20.0 2023-01-23