Update changelog

Author: taiki-e

CHANGELOG.md

@@ -12,6 +12,10 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- Performance improvements.
+
+- Documentation improvements.
+
 ## [0.6.34] - 2025-01-16
 
 - Fix `--mutually-exclusive-features` interacting with optional dependencies. ([#261](https://github.com/taiki-e/cargo-hack/pull/261), thanks @xStrom)