docs: netdev: update the netdev infra URLs

Some corporate proxies block our current NIPA URLs because
they use a free / shady DNS domain. As suggested by Jesse
we got a new DNS entry from Konstantin - netdev.bots.linux.dev,
use it.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>