Add CHANGELOG entry for new SYSEMU functions

Author: voidc

CHANGELOG.md

@@ -7,6 +7,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 - Added Netlink protocol families to the `SockProtocol` enum
 (#[1289](https://github.com/nix-rust/nix/pull/1289))
+- Added wrapper functions for `PTRACE_SYSEMU` and `PTRACE_SYSEMU_SINGLESTEP`.
+  (#[1300](https://github.com/nix-rust/nix/pull/1300))
 ### Changed
 - Expose `SeekData` and `SeekHole` on all Linux targets
 (#[1284](https://github.com/nix-rust/nix/pull/1284))