specs: Introduction to High Priority Traffic Path

Introduction in spec file outlining requirement for
High Priority Traffic Path.

Change-Id: I4b772e8cbb86838547cb09f50a5c0872ef6eb21d
Signed-off-by: Mark D. Gray <mark.d.gray@intel.com>
Reviewed-by: Billy O'Mahony <billy.o.mahony@intel.com>
Reviewed-by: Tom Herbert <therbert@redhat.com>
Reviewed-by: Al Morton <acmorton@att.com>