update CHANGELOG

CHANGELOG.rst

@@ -5,6 +5,17 @@ All notable changes to this project will be documented in this file.
 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>`_.
 
+5.5.4 - 2024-01
+----------------
+
+- Type annotate api.py's functions.
+- Deprecate camel case function names in api.py.
+- Start using same requirements_docs.txt in readthedocs and tox.
+- Enable autodoc and typehints in the API documentation.
+- Fix docstring errors in the io module.
+- Add changelog to the documentation.
+
+
 5.5.3 - 2024-01
 ----------------
 - Add type stub for cppcore module to make Python recognise the C++ functions' arguments and return values.