Update CHANGELOG.md

Author: ns-vasilev

CHANGELOG.md

@@ -11,6 +11,8 @@ All notable changes to this project will be documented in this file.
 #### Added
 - Add `dependabot.yml`
   - Added in Pull Request [#21](https://github.com/space-code/validator/pull/21).
+- Add `URLValidationRule`.
+  - Added in Pull Request [#23](https://github.com/space-code/validator/pull/23).
 
 #### Updated
 - Update `Mintfile`