update changelog for v2.2.1

Author: archmoj

CHANGELOG.md

@@ -9,6 +9,12 @@ To see all merged commits on the master branch that will be part of the next plo
 
 where X.Y.Z is the semver of most recent plotly.js release.
 
+## [2.2.1] -- 2021-07-06
+
+### Fixed
+ - Fix to improve sanitizing href inputs for SVG and HTML text elements [[#5803](https://github.com/plotly/plotly.js/pull/5803)]
+
+
 ## [1.58.5] -- 2021-07-06
 
 ### Fixed