docs: update CHANGELOG for v2.1.0

Author: EfeSidal

CHANGELOG.md

@@ -5,7 +5,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [0.1.0] - 2026-04-06
+## [Unreleased]
+
+## [2.1.0] - 2026-04-07
 
 ### Added
 - **PE & ELF Parsing Engine**: Initial implementation for extracting file metadata and section headers using the `goblin` crate.