[skip ci] add a CHANGELOG section for the next release

Author: asomers

CHANGELOG.md

@@ -3,15 +3,17 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
-## [0.26.1] - 2022-11-29
+## [Unreleased] - ReleaseDate
 ### Added
 ### Changed
 ### Fixed
+### Removed
+
+## [0.26.1] - 2022-11-29
+### Fixed
 - Fix UB with `sys::socket::sockopt::SockType` using `SOCK_PACKET`.
   ([#1821](https://github.com/nix-rust/nix/pull/1821))
 
-### Removed
-
 ## [0.26.0] - 2022-11-29
 ### Added