doc: update release notes for 20.02
doc: update release notes for 20.02

Fix grammar, spelling and formatting of DPDK 20.02 release notes.

Signed-off-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>
Acked-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@redhat.com>

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