tracing: Append prompt in /debug/tracing/README file

append prompt in /debug/tracing/README file.

This is trivial issue. Fix typo Mini Howto file(README) for ftrace.

[ Impact: cleanup ]
Signed-off-by: GeunSik Lim <geunsik.lim@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: williams <williams@redhat.com>
LKML-Reference: <1242289418.31161.45.camel@centos51>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/trace/trace.c

@@ -2380,7 +2380,7 @@ static const char readme_msg[] =
 	"# echo print-parent > /debug/tracing/trace_options\n"
 	"# echo 1 > /debug/tracing/tracing_enabled\n"
 	"# cat /debug/tracing/trace > /tmp/trace.txt\n"
-	"echo 0 > /debug/tracing/tracing_enabled\n"
+	"# echo 0 > /debug/tracing/tracing_enabled\n"
 ;
 
 static ssize_t