Update objtrace usage in Documentation/trace/events.rst

[renhai_lenovo]

Documentation: trace/objtrace: Move the line entering the trace
directory to the first step, so that the commands in the first step
can be executed smoothly.

    Signed-off-by: Renhai <rh_king@xxxxxxx>

diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index 52ac8ca8ab64..d5fadf7966de 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -583,6 +583,7 @@ The following commands are supported:

   .. code-block::

+    # cd /sys/kernel/debug/tracing/
      # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events

   Secondly, we can get the value dynamically based on the object:
@@ -597,7 +598,6 @@ The following commands are supported:
      # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' >
./events/kprobes/ \
        p_bio_add_page_0/trigger

-     # cd /sys/kernel/debug/tracing/
      # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events
      # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' >
./events/kprobes/p_bio_add_page_0/trigger