Add a few trace.py examples in tutorial.md
Add a few trace.py examples in tutorial.md

Signed-off-by: Yonghong Song <e76892bbe783db2f627de1232e139db4de43da60@fb.com>

brendangregg/bcc,tuxology/bcc,mcaleavya/bcc,iovisor/bcc,tuxology/bcc,brendangregg/bcc,mcaleavya/bcc,brendangregg/bcc,iovisor/bcc,iovisor/bcc,tuxology/bcc,tuxology/bcc,mcaleavya/bcc,iovisor/bcc,mcaleavya/bcc,iovisor/bcc,brendangregg/bcc,mcaleavya/bcc,brendangregg/bcc,tuxology/bcc