docs: rework trace processor docs am: cb45a21340 am: 8aa752bec6
docs: rework trace processor docs am: cb45a21340
am: 8aa752bec6

Change-Id: Ic78119729d27301758b69865e200f13931022479

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto