chore: update changelog

Author: Alenar

CHANGELOG.md

@@ -11,6 +11,8 @@ As a minor extension, we have adopted a slightly different versioning convention
 
 - Build and publish both a `stable` version (for release networks) and an `unstable` version (for testing networks) of the explorer.
 
+- **UNSTABLE** Implement a **EXPERIMENTAL** caching mechanism in client certificate verification to improve performance.
+
 - Crates versions:
 
 | Crate | Version |