We don't currently have a clear place in the documentation to describe
the roles and responsibilities of a maintainer. Lets create one so we
can. I've moved a few small bits out of other files to try and keep
everything in one place.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221117172532.538149-5-alex.bennee@linaro.org>