chore(changelog): add git-cliff configuration

[orhun]

closes #613

Now we don't need to update the changelog with every commit, just run the following command before creating a release for automatically populating it from the commits:

NEXT_VERSION="1.0.0"
git cliff --unreleased --tag "${NEXT_VERSION}" --prepend docs/docs/changelog.md

It looks like this:

### Added

- Add search local by @raphamorim
- Added tabs-active-foreground config by @rdbo in [#619](https://github.com/raphamorim/rio/pull/619)

### Changed

- Add git-cliff configuration
- Fix flake by @TornaxO7 in [#627](https://github.com/raphamorim/rio/pull/627)
- Change docs structure (readd deleted under configs) by @raphamorim
- Change docs structure by @raphamorim
- Update changelog by @raphamorim
- Format cargo by @raphamorim
- Unschedule pending events by @raphamorim
- Update frame scheduling by @raphamorim
- Frame scheduler by @raphamorim
- Enable features on parking_lot like hardware-lock-elision (x86) and deadlock_detection by @raphamorim
- Update changelog by @raphamorim
- Update docs by @raphamorim
- Update version on install by @raphamorim
- Update changelog by @raphamorim

### Fixed

- Fix links by @raphamorim
- Fixed tabs-active-highlight config key by @rdbo in [#618](https://github.com/raphamorim/rio/pull/618)

### Removed

- Remove grab cursor on macos and place default instead by @raphamorim
- Remove tokio runtime by @raphamorim
- Remove deadlock_detection feature flag by @raphamorim
- Remove rust-toolchain.toml by @raphamorim

Let me know if you want any updates in the changelog. Maybe we can filter out everything except GitHub PRs but then I fear that we might lose some valuable commits that are directly pushed to main.

For reference, check out https://git-cliff.org/docs/