doc: fix subport configuration in ip pipeline guide
doc: fix subport configuration in ip pipeline guide

Update the user guide of ip pipeline sample application
to reflect the changes in command line arguments.

Fixes: 54a298e5f7f4 ("examples/ip_pipeline: update subport rate dynamically")

Signed-off-by: Savinay Dharmappa <b9bdbfc60b49ae384b99e3313b3f20d055baeacb@intel.com>
Acked-by: Cristian Dumitrescu <25468b8a3698eeb3c368247f8635924bb4a1ce2c@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk