chore(docs): remove lib/zaxcel/README.md and announce centralized docs in CHANGELOG

Author: chamod-gamage

CHANGELOG.md

@@ -5,6 +5,12 @@ 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).
 
+## [Unreleased]
+
+### Removed
+
+- Removed `lib/zaxcel/README.md`. Documentation is centralized in the root `README.md`.
+
 ## [0.1.1] - 2025-10-29
 
 ### Changed
@@ -27,3 +33,4 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 [0.1.0]: https://github.com/angellist/zaxcel/releases/tag/v0.1.0
 [0.1.1]: https://github.com/angellist/zaxcel/releases/tag/v0.1.1
+[Unreleased]: https://github.com/angellist/zaxcel/compare/v0.1.1...HEAD