Update CHANGELOG.md

Author: sonallux

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+- Update links to Spotify documentation
 
 ## [4.0.0]
 - Adjust the categories of some endpoints to match with the official [Spotify Web API Reference](https://developer.spotify.com/documentation/web-api). No endpoint have been removed, they just got moved to other categories.