docs: add a changelog

CHANGELOG.md

+
+# CHANGELOG
+
+## Version 0.2.0 (2020-04-05)
+### New features
+
+- show the version release date in the changelog
+
+### Bug fixes
+
+- remove an extra line in the changelog template
+
+
+## Version 0.1.0 (2020-04-05)
+### New features
+
+- autogenerate changelog with hg using conventionnal commits
+
+### Documentation
+
+- add a readme
+
+### Continuous integration
+
+- add a tox.ini and pyproject.toml (black) files
+
+