<!-- When adding an entry to the Changelog:

- Please follow the Keep a Changelog: http://keepachangelog.com/ guidelines.
- Please insert your changelog line ordered by PR ID.
- Make sure you add your entry to the correct section (schema or tooling).

Thanks, you're awesome :-) -->

## Unreleased

### Schema Changes

#### Breaking changes

#### Bugfixes
* Fix broken link in docs for vulnerability.id. #2328

#### Added

* Added `volume.*` as beta field set. #2269
* Advanced `process.env_vars` to GA. #2315
* Advanced `process.io` and `process.tty` fields to GA. #2317
* Added `threat.indicator.id`. #2324
* Added `process.group` to generated schemas. #2335

#### Improvements

* Define base encoding of `x509.serial_number`. #2383

#### Deprecated

### Tooling and Artifact Changes

#### Breaking changes

#### Bugfixes

#### Added

* Documentation in README.md providing instruction on contributions to ECS during the OTel donation #2325

#### Improvements

#### Deprecated

<!-- All empty sections:

## Unreleased

### Schema Changes

#### Breaking changes

#### Bugfixes

#### Added

#### Improvements

#### Deprecated

### Tooling and Artifact Changes

#### Breaking changes

#### Bugfixes

#### Added

#### Improvements

#### Deprecated

-->