Docs/admin-guide/mm/damon/usage: use sysfs interface for tracepoints example

Patch series "mm/damon: make DAMON debugfs interface deprecation
unignorable".

DAMON debugfs interface is deprecated in February 2023, by commit
5445fcbc4c ("Docs/admin-guide/mm/damon/usage: add DAMON debugfs
interface deprecation notice").  Make the fact unable to be easily ignored
by removing an example usage from the document (patch 1), renaming the
config (patch 2), adding a deprecation notice file to the debugfs
directory (patches 3-5), and renaming the debugfs file that essnetial to
be used for real use of DAMON (patches 6-9).


This patch (of 9):

DAMON tracepoints example on the DAMON usage document is using DAMON
debugfs interface, which is deprecated.  Use its alternative, DAMON sysfs
interface.

Link: https://lkml.kernel.org/r/20240130013549.89538-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20240130013549.89538-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/admin-guide/mm/damon/usage.rst

@@ -579,11 +579,11 @@ monitoring results recording.
 While the monitoring is turned on, you could record the tracepoint events and
 show results using tracepoint supporting tools like ``perf``.  For example::
 
-    # echo on > monitor_on
+    # echo on > kdamonds/0/state
     # perf record -e damon:damon_aggregated &
     # sleep 5
     # kill 9 $(pidof perf)
-    # echo off > monitor_on
+    # echo off > kdamonds/0/state
     # perf script
     kdamond.0 46568 [027] 79357.842179: damon:damon_aggregated: target_id=0 nr_regions=11 122509119488-135708762112: 0 864
     [...]