Update changelog

Author: lcharette

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [v4.2.1]
 - Fix Italian translation ([#950])
+- User Registration fails when trying to register two accounts with the same email address ([#953])
 
 ## [v4.2.0]
 ### Changed Requirements
@@ -708,6 +709,7 @@ See [http://learn.userfrosting.com/upgrading/40-to-41](Upgrading 4.0.x to 4.1.x
 [#919]: https://github.com/userfrosting/UserFrosting/issues/919
 [#940]: https://github.com/userfrosting/UserFrosting/issues/940
 [#950]: https://github.com/userfrosting/UserFrosting/issues/950
+[#953]: https://github.com/userfrosting/UserFrosting/issues/953
 
 [v4.2.0]: https://github.com/userfrosting/UserFrosting/compare/v4.1.22...v4.2.0
 [v4.2.1]: https://github.com/userfrosting/UserFrosting/compare/v4.2.0...v4.2.1