Docs/admin-guide/mm/damon/usage: fixup missed :ref: keyword

Docs/admin-guide/mm/damon/usage: fixup missed :ref: keyword

Patch series "mm/damon: misc fixups for documents, comments and its
tracepoint".

This patchset contains miscellaneous simple fixups for documents, comments and
tracepoint of DAMON.

This patch (of 11):

A cross-link reference in DAMON usage document is missing ':ref:' Sphynx
keyword.  Fix it.

Link: https://lkml.kernel.org/r/20230907022929.91361-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230907022929.91361-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>