Remove CHANGELOG.md, link GitHub Releases in README

Eliminates double maintenance — release notes already live on GitHub Releases.

Author: Dennis Braun

CHANGELOG.md

@@ -249,7 +249,7 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for development setup and guidelines.
 
 ## Changelog
 
-See [CHANGELOG.md](CHANGELOG.md) for a detailed list of changes per version.
+See [GitHub Releases](https://github.com/itsDNNS/docsight/releases) for release notes and changelogs.
 
 ## License