[docs] Add a section on AI-generated content to the developer policy

Governments around the world are starting to require labelling for
AI-generated content, and some LLVM stakeholders have asked if LLVM
contains AI-generated content. Defining a policy on the use of AI tools
allows us to answer that question affirmatively, one way of the other.

The policy proposed here allows the use of AI tools in LLVM
contributions, flowing from the idea that any contribution is fine
regardless of how it is made, as long as the contributor has the right
to license it under the project license.

Author: rnk

llvm/docs/DeveloperPolicy.rst

@@ -1301,4 +1301,23 @@ to move code from (e.g.)  libc++ to the LLVM core without concern, but that code
 cannot be moved from the LLVM core to libc++ without the copyright owner's
 permission.
 
+.. _ai contributions:
+
+AI generated contributions
+--------------------------
+
+Artificial intelligence systems raise many questions around copyright that have
+yet to be answered. Our policy on AI tools is guided by our copyright policy:
+contributors are responsible for ensuring that they have the right to contribute
+code under the terms of our license, typically meaning that either they, their
+employer, or their collaborators hold the copyright. Using AI tools to
+regenerate copyrighted material does not remove the copyright, and contributors
+are responsible for ensuring that such material does not appear in their
+contributions.
+
+As such, the LLVM policy is that contributors are permitted to to use artificial
+intelligence tools to produce contributions, provided that they have the right
+to license that code under the project license. Contributions found to violate
+this policy will be removed just like any other offending contribution.
+
 .. _LLVM Discourse forums: https://discourse.llvm.org