Doc: More troubleshooting hints for perf profiler

Apparently the chosen event type influences the stability of the
recording process and you can change the event type using the
additional arguments.

Change-Id: I0e1982d4d469e1e4d17e2aa01d3c5166ce8817a3
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>