trace-cmd: Document "trace-cmd report --cpu ..." option

Added description of "trace-cmd report --cpu ..." option in
"trace-cmd report --help" output and in "trace-cmd report" man page.

Link: https://lore.kernel.org/linux-trace-devel/20200717075741.74775-3-tz.stoyanov@gmail.com

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2 files changed