Docs/admin-guide/damon/reclaim: document 'skip_anon' parameter

Document the newly added 'skip_anon' parameter of DAMON_RECLAIM, which can
be used to avoid anonymous pages reclamation.

Link: https://lkml.kernel.org/r/20221205230830.144349-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: sjp38

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

@@ -205,6 +205,15 @@ The end physical address of memory region that DAMON_RECLAIM will do work
 against.  That is, DAMON_RECLAIM will find cold memory regions in this region
 and reclaims.  By default, biggest System RAM is used as the region.
 
+skip_anon
+---------
+
+Skip anonymous pages reclamation.
+
+If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
+pages.  By default, ``N``.
+
+
 kdamond_pid
 -----------