maintainers: update for testpmd
maintainers: update for testpmd

Add Aman Singh as co-maintainer of testpmd.

Make the title description more accurate for this tool.

Signed-off-by: Aman Singh <fb393a3ad4e707279057dbfe1c724dcc482648dd@intel.com>
Acked-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>
Signed-off-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>

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