doc: add Linux flower support check in TAP guide
doc: add Linux flower support check in TAP guide

The flow API is supported in TAP PMD if flower is supported in Linux.
Some commands are combined to suggest a convenient check of its support
by the running kernel.

Signed-off-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>
Acked-by: Pascal Mazon <f8a8edbbccb52ea5be26461cb34f4752a08c0c30@6wind.com>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

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