docs: netdev: Fix typo in Signed-off-by tag

s/of/off/

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Fixes: e110ba65

 ("docs: netdev: add note about Changes Requested and revising commit messages")
Link: https://lore.kernel.org/r/20240527103618.265801-2-thorsten.blum@toblux.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>