Update Changelog

Author: Pauliusd01

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -5,7 +5,9 @@ All notable changes to the input system package will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-[Unreleased] - yyyy-mm-dd
+## [Unreleased] - yyyy-mm-dd
+
+
 
 ## [1.20.0] - 2026-07-21