Use content of change log file for release letter

Author: ckunki

doc/changes/unreleased.md

@@ -9,3 +9,6 @@ For additional information, refer to [customization](../user_guide/customization
 
 ## 📚 Documentation
 * Added documentation on nox task plugins for users and developers.
+
+## 🐞 Fixed
+* Updated templates for GH workflows to add content of changes file for release letter

exasol/toolbox/templates/github/workflows/build-and-publish.yml

@@ -34,4 +34,5 @@ jobs:
         run: >
           gh release create ${GITHUB_REF_NAME}
           --title ${GITHUB_REF_NAME}
+          --notes-file ./doc/changes/changes_${GITHUB_REF_NAME}.md
           dist/*