Add changelog entry

Author: Amanieu

CHANGELOG.md

@@ -4,10 +4,12 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased] - ReleaseDate
+### Added
 - Added Netlink protocol families to the `SockProtocol` enum
 (#[1289](https://github.com/nix-rust/nix/pull/1289))
-### Added
 ### Changed
+- Expose `SeekData` and `SeekHole` on all Linux targets
+(#[1284](https://github.com/nix-rust/nix/pull/1284))
 ### Fixed
 ### Removed