docs/code-provenance: make the exception process more prominent

QEMU's AI generated content policy does not flesh out the exception
process yet.  Do it, while at the same time keeping things informal: ask
contributors to explain what they would like to use AI for, and let them
reach a consensus with the project on why it is credible to claim DCO
compliance in that specific scenario.

In other words, exceptions do not "solve the AI copyright problem".  They
take a position that a reasonable contributor could have, and assert that
we're comfortable with the argument.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed