As Stephen is no longer actively maintaining the uboot-test-hooks,
and the repo itself has been moved to source.denx.de, update the
Contributing.md with up-to-date information on how patches should
be sent against this repo.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
... which contains details of preferred patch subject prefix. This makes
it easier to see which patches apply to this repo.
Signed-off-by: Stephen Warren <swarren@nvidia.com>