CHANGELOG.md holds an [Unreleased] section with what the first release
v1.0.0 will contain, in the groups Breaking, Added, Changed and Fixed.
tools/changelog.py checks the convention of ADR-0006 (Unreleased first,
descending versions, dates, a Breaking entry needs a new major and a new major
needs one) and prints the notes of a release for the release page. The
release process guide uses both.
Task: MIL-004#2