Correct changelog link

Author: code-asher

CHANGELOG.md

@@ -22,7 +22,7 @@ Code v99.99.999
 
 ## Unreleased
 
-## [4.21.2](https://github.com/coder/code-server/releases/tag/v4.21.1) - 2021-02-28
+## [4.21.2](https://github.com/coder/code-server/releases/tag/v4.21.2) - 2021-02-28
 
 Code v1.86.2