docs: netdev: clarify the need to sending reverts as patches

We don't state explicitly that reverts need to be submitted
as a patch. It occasionally comes up.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230327172646.2622943-1-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>