ethdev: fix doc of flow action
ethdev: fix doc of flow action

The struct rte_flow_action was missing from DPDK API documentation.

Fixes: 3850cf0c8c37 ("ethdev: add tunnel encap/decap actions")
Cc: stable@dpdk.org

Signed-off-by: Jan Viktorin <077cce75738556d99b8362c6a64d5bba1ba87459@cesnet.cz>
Acked-by: Ori Kam <dd654df5de18ba542acfaea52fe1a0799392087d@nvidia.com>
Acked-by: Aman Deep Singh <fb393a3ad4e707279057dbfe1c724dcc482648dd@intel.com>

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