Changelog (or release notes) helps developers to stay up to date with project changes and helps migrating to new versions.
Create a changelog entry for every version. The latest version should come first.
This improves changelog readability and makes it easy to find relevant changes. There are multiple ways to categorize changes - choose whatever suits your project best. Here are the most common categories:
When grouping changes doesn't make sense you can label them a prefix, for example '[docs] ...'.