Add AI tooling policy to CONTRIBUTING.md (#4844)

This came up in a few conversations at the contributor summit, so I
wanted to add a short blurb about it to the contributor guide.
Contributors own the quality of what they submit, and there are no
restrictions on AI tooling as long as the contribution meets the
project's quality bar.

This was generated by AI but verified, with love, by a human.

Signed-off-by: Madelyn Olson <madelyneolson@gmail.com>

CONTRIBUTING.md

@@ -75,6 +75,12 @@ If you're contributing code to the Valkey project in any other form, including
 sending a code fragment or patch via private email or public discussion groups,
 you need to ensure that the contribution is in accordance with the DCO.
 
+## Use of AI tools
+
+You own the quality of the code that you submit to the project. The Valkey
+project doesn't impose any limitations on the use of AI tooling as long as the
+contribution meets the quality bar of the project.
+
 ## How to provide a patch or a new feature
 
 1. If it is a major feature or a semantical change, please don't start coding