perf intel-pt: Improve PT documentation slightly

Document the higher level --insn-trace etc. perf script options.

Include the howto how to build xed into the manpage

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20201014035346.4772-1-andi@firstfloor.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>