doc: update bnxt guide
doc: update bnxt guide

This patch reformats the Broadcom PMD driver documentation.

Also since the PMD now loads on a VF interface, update the
documentation accordingly.

Signed-off-by: Ajit Khaparde <01965fbd61169dc18f3fb5e13de7f67d298f8924@broadcom.com>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

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