It's a new year; update the copyright strings for our
help/version/about information and for our documentation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220120124713.288303-1-peter.maydell@linaro.org