add missing CHANGELOG link

Author: Thinh Nguyen

CHANGELOG.md

@@ -67,5 +67,6 @@ Observes [Semantic Versioning](https://semver.org/spec/v2.0.0.html) standard and
 [0.1.2]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.2
 [0.1.1]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.1
 [0.1.0]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.0
+[0.1.0b4]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.0b4
 [0.1.0b0]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.0b0
 [0.1.0a5]: https://github.com/datajoint/element-array-ephys/releases/tag/0.1.0a5