Changelog Entry template

Canonical template for the Changelog Entry format.

## [Version] - YYYY-MM-DD

### Added
- [New feature, described from the user's perspective] (#PR or #issue)

### Changed
- [Behavior change that does not break existing usage] (#PR)

### Deprecated
- [Feature scheduled for removal in a future version, with migration note] (#PR)

### Removed
- [Feature deleted in this version, with migration note] (#PR)

### Fixed
- [Bug fix, described from the user's perspective] (#PR)

### Security
- [Security fix, often with CVE link or advisory link] (#PR)