policy: Clarify that "AI" means specific things.

(cherry picked from commit 954e2f33541afbb55f02450ed6cf6c1f418a3ab6)

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,4 @@
-- [ ] I confirm that I am the author of this code and release it to the SDL project under the Zlib license. This contribution does not contain code from other sources, including AI generated code.
+- [ ] I confirm that I am the author of this code and release it to the SDL project under the Zlib license. This contribution does not contain code from other sources, including code generated by a Large Language Model ("AI").
 
 <!--- Provide a general summary of your changes in the Title above -->
 

AGENTS.md

@@ -1,5 +1,8 @@
 AI may not be used to generate code for contributions to this project.
 
+"AI" in this case means a Large Language Model ("LLM"), such as ChatGPT,
+Claude, Copilot, Grok, etc.
+
 AI-generated code is based upon sources of unknown origins and may not be
 compatible with the Zlib license, or may introduce conflicting license terms
 if they include code from other projects.