Document DAMON_STAT usage and add a link to it on DAMON admin-guide page.
Link: https://lkml.kernel.org/r/20250604183127.13968-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>