perf script: Fix documentation errors

perf script: Fix documentation errors

This commit fixes two errors in documents for perf-script-python and
perf-script-perl as below:

- /sys/kernel/debug/tracing events -> /sys/kernel/debug/tracing/events/
- trace_handled -> trace_unhandled

Signed-off-by: SeongJae Park <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tom Zanussi <[email protected]>
Fixes: cff68e582237 ("perf/scripts: Add perf-trace-python Documentation")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>