doc: add igb guide

This patch adds user guide specifically for igb NIC, like ixgbe,
to list all the supported features and known issues.

Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>

doc/guides/nics/igb.rst

@@ -0,0 +1,38 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2017 Intel Corporation.
+
+IGB Poll Mode Driver
+====================
+
+The IGB PMD (``librte_pmd_e1000``) provides poll mode driver
+support for Intel 1GbE nics.
+
+Features
+--------
+
+Features of the IGB PMD are:
+
+* Multiple queues for TX and RX
+* Receiver Side Scaling (RSS)
+* MAC/VLAN filtering
+* Packet type information
+* Double VLAN
+* IEEE 1588
+* TSO offload
+* Checksum offload
+* TCP segmentation offload
+* Jumbo frames supported
+
+
+Limitations or Known issues
+---------------------------
+
+
+Supported Chipsets and NICs
+---------------------------
+
+- Intel 82576EB 10 Gigabit Ethernet Controller
+- Intel 82580EB 10 Gigabit Ethernet Controller
+- Intel 82580DB 10 Gigabit Ethernet Controller
+- Intel Ethernet Controller I210
+- Intel Ethernet Controller I350

doc/guides/nics/index.rst

@@ -23,6 +23,7 @@ Network Interface Controller Drivers
     enic
     fm10k
     i40e
+    igb
     ixgbe
     intel_vf
     kni