docs: Fixup cpudist pid example in man page
docs: Fixup cpudist pid example in man page

-P prints all by process id
-p prints specific process id

also fixed port num in example

iovisor/bcc,iovisor/bcc,iovisor/bcc,iovisor/bcc,brendangregg/bcc,brendangregg/bcc,brendangregg/bcc,brendangregg/bcc,iovisor/bcc,brendangregg/bcc