[doc] #1: Introduce CHANGELOG.md

CHANGELOG.md

+## v0.3.0 (2Xth April 2021)
+- #1, !13: Create Python package / Repository refactor:
+
+### Dev env
+- Rename repository, package, and folder from `licence-g1` to `g1-monetary-license`
+- Create Python package with Poetry
+- Set-up PyPI and PyPI test jobs
+- Introduce `release.sh`
+- Get rid of broken M$ GH mirroring
+
+### Documentation
+- License repository under GPL-3.0-or-later
+- Update `README.md`
+- Introduce `CONTRIBUTING.md`
+- Introduce `CHANGELOG.md`
+
+### Content
+- French and English licenses proofread
+
+Thanks @Moul
+
+## v0.2.9 (11th April 2021)
+- !12, !11: Add Portuguese translation
+- !10: Improve Spanish license
+
+Thanks Pedro Almeida, @Vivakvo, @kapis