Documentation: Fix a typo on trace/osnoise-tracer

s/RUNTIME IN USE/RUNTIME IN US/

Link: https://lkml.kernel.org/r/43e5160422a967218aa651c47f523e8d32d6a59e.1624872608.git.bristot@redhat.com



Fixes: bce29ac9 ("trace: Add osnoise tracer")
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>