doc: remove redundant information from debug guide
doc: remove redundant information from debug guide

Remove redundant information from section Performance issue isolation.
Re-word for section header for packet capture.

Fixes: 08db7bde1617 ("doc: add guide for debug and troubleshoot")

Signed-off-by: Vipin Varghese <b0b9508e3fd3e721e16f75bda9fcfd493661c711@intel.com>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

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