Updated CHANGELOG

CHANGELOG.md

@@ -2,6 +2,9 @@
 All major and minor version changes will be documented in this file. Details of patch-level version changes can be found in [commit messages](https://github.com/gchq/CyberChef/commits/master).
 
 
+### [9.21.0] - 2020-06-12
+- Node API now exports `magic` operation [@d98762625] | [#1049]
+
 ### [9.20.0] - 2020-03-27
 - 'Parse ObjectID Timestamp' operation added [@dmfj] | [#987]