docs: introduce dedicated page about code provenance / sign-off

Currently we have a short paragraph saying that patches must include
a Signed-off-by line, and merely link to the kernel documentation.
The linked kernel docs have a lot of content beyond the part about
sign-off an thus are misleading/distracting to QEMU contributors.

This introduces a dedicated 'code-provenance' page in QEMU talking
about why we require sign-off, explaining the other tags we commonly
use, and what to do in some edge cases.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
3 files changed