Add/update ai contribution guideline.

CONTRIBUTING.rst

@@ -1 +1,4 @@
 Detailed contribution guidelines are available as part of our documentation at https://axelrod.readthedocs.io/en/latest/how-to/contributing/index.html
+
+Our policy on the use of AI tools is at
+https://axelrod.readthedocs.io/en/latest/how-to/contributing/use_of_ai_tools.html

README.rst

@@ -110,16 +110,15 @@ Examples
 Contributing
 ------------
 
-All artisanal contributions are welcome!
-
-*Code Generation Policy*:
-
-*We do not accept any content that has been created with the assistance of generative code tools.*
+All contributions are welcome!
 
 You can find helpful instructions about contributing in the
 documentation:
 https://axelrod.readthedocs.io/en/stable/how-to/contributing/index.html
 
+Our policy on the use of AI tools is at
+https://axelrod.readthedocs.io/en/stable/how-to/contributing/use_of_ai_tools.html
+
 Publications
 ------------
 

docs/how-to/contributing/index.rst

@@ -10,6 +10,7 @@ Contents:
    :maxdepth: 2
 
    guidelines.rst
+   use_of_ai_tools.rst
    setting_up_the_environment.rst
    strategy/index.rst
    library/index.rst

docs/how-to/contributing/use_of_ai_tools.rst

@@ -0,0 +1,21 @@
+Use of AI tools
+===============
+
+You may use AI tools (code assistants, large language models) when
+contributing to the library. If you do, the description of your pull request
+must say which parts were AI-generated. Autocomplete and spelling fixes do not
+count.
+
+We also require the following:
+
+- You are responsible for your contribution: you should understand it, have
+  tested it and be able to explain every line.
+- Keep it small and self-contained. Generated code should be documented,
+  readable and isolated (for example one strategy class plus its tests) so that
+  it can be cleanly removed later. We will not accept large volumes of generated
+  code.
+- A new strategy should either come from the published literature, with a
+  reference in the :ref:`bibliography`, or be qualitatively new. A generated
+  variant of a strategy already in the :ref:`strategies-index` adds no value.
+- The maintainers do not commit to maintaining AI-generated code, and we may
+  remove it if it becomes a maintenance burden.