This patch adds "Limitations or Known issues" section for
i40e PMD, including two items:
1. MPLS packet classification on X710/XL710
2. 16 Byte Descriptor cannot be used on DPDK VF
3. Link down with i40e kernel driver after DPDK application exist
Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
edf1b61831