Add CC-BY-4.0 license to the AI policy (#5232)

* Add CC-BY-4.0 license to the AI policy

Added license information to the AI contributions policy.

* Update AI_POLICY.md

Co-authored-by: Rocco Meli <r.meli@bluemail.ch>

---------

Co-authored-by: Rocco Meli <r.meli@bluemail.ch>

Author: IAlibay

AI_POLICY.md

@@ -1,6 +1,7 @@
 # 🤖 MDAnalysis AI-generated contributions policy 🤖
 
 ### Version: 1.0 (2026-02-03)
+### License: [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)
 
 This document defines the [MDAnalysis organization's](https://github.com/MDAnalysis/) policy regarding AI-generated content. This policy applies to all aspects of the MDAnalysis project, including all the GitHub repositories under the organization.