docs: v1.15.0 release date

Author: Nelson-numerical-software

CHANGELOG.md

@@ -5,7 +5,7 @@ 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).
 
-## 1.15.0 - (UNRELEASED)
+## 1.15.0 - (2025-11-21)
 
 Starting with v1.15, Nelson for Windows is officially signed with a Certum-issued code-signing certificate.
 This is a major security milestone, ensuring the authenticity and integrity of Nelson’s Windows releases.