Add changelog

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 418665d..26d5df2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 All notable changes to this project will be documented in this file.
 
+The changelog of the `rustfilt` crate can be found at [crates/rustfilt/CHANGELOG.md](crates/rustfilt/CHANGELOG.md).
+
 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).
 

crates/rustfilt/CHANGELOG.md

diff --git a/crates/rustfilt/CHANGELOG.md b/crates/rustfilt/CHANGELOG.md
new file mode 100644
index 0000000..fd7b5c1
--- /dev/null
+++ b/crates/rustfilt/CHANGELOG.md
@@ -0,0 +1,9 @@
+# Changelog
+
+All notable changes to the `rustfilt` crate will be documented in this file.
+
+## [Unreleased]
+
+### Performance
+
+- Improve performance of name demangling.