[doc] Add changelog section for version 4.0.0

Assisted-by: Claude <noreply@anthropic.com>

Author: Wentzell

doc/ChangeLog.md

@@ -1,5 +1,33 @@
 # Changelog
 
+## Version 4.0.0
+
+omegamaxent_interface version 4.0.0 is a compatibility release for TRIQS version 4.0.0 that
+* introduces compatibility with TRIQS 4.0 (renamed `triqs.gf` Python module to `triqs.gfs`)
+* uses the latest [app4triqs](https://github.com/TRIQS/app4triqs) skeleton (python-only variant)
+
+We thank all contributors: Jennifer Coulter, Thomas Hahn, Alexander Hampel, Henri Menke, Dylan Simon, Nils Wentzell
+
+Find below an itemized list of changes in this release.
+
+### General
+* Run port_to_triqs4 porting script for the triqs.gf -> triqs.gfs module rename
+* Use the latest app4triqs/4.0.x skeleton
+* Fetch and build the OmegaMaxEnt program from a fork (Thoemi09/OmegaMaxEnt)
+* Fix invalid escape sequences in string literals
+
+### jenkins
+* Migrate to the new k8s-based Jenkins system
+* Link to openblas on macOS
+
+### ghactions
+* Add a workflow to publish the package to PyPI
+* Link to openblas on macOS
+
+### doc
+* Add FI support notice to README.md
+
+
 ## Version 3.3.0
 
 omegamaxent_interface version 3.3.0 is a compatibility release for TRIQS version 3.3.0.