docs: update Release Notes for version 3.15.0

- Added release date and version number for 3.15.0.
- Included new section for build and packaging improvements.
- Documented exclusion of system libraries from the tarball to
  reduce package size and avoid conflicts.

These changes enhance clarity and provide users with
important updates regarding the release.

Author: AnarManafov

ReleaseNotes.md

@@ -1,6 +1,6 @@
 # Release Notes
 
-## Unreleased
+## [3.15.0] - 2025-10-08
 
 ### 🎉 New Features
 
@@ -21,7 +21,11 @@
 - **dds-session**: Enhanced README with lightweight session examples and configuration guides
 - **dds-submit**: Improved documentation including new `--path` option details
 
-### 🚀 For Users
+### � Build & Packaging Improvements
+
+- **Optimized Tarball**: System libraries (libc, libm, ld-linux) are now excluded from the tarball to reduce package size and avoid conflicts with system installations
+
+### �🚀 For Users
 
 These documentation improvements make DDS much easier to understand and use: