update changelog

Author: Freax13

Changelog.md

@@ -5,11 +5,16 @@
 ## New Features
 
 - [add SMAP helpers](https://github.com/rust-osdev/x86_64/pull/566)
+- [add ability to add iomap to TSS](https://github.com/rust-osdev/x86_64/pull/194)
 
 ## Fixes
 
 - [fix docs.rs build](https://github.com/rust-osdev/x86_64/pull/569)
 
+## Other Improvements
+
+- [Bump actions/checkout from 5 to 6](https://github.com/rust-osdev/x86_64/pull/571)
+
 # 0.15.3 – 2025-11-19
 
 ## New Features