MAINTAINERS: add Chris and Kairui as the swap maintainer

We have been collaborating on a systematic effort to clean up and improve
the Linux swap system, and might as well take responsibility for it.

Link: https://lkml.kernel.org/r/20251102-swap-m-v1-1-582f275d5bce@kernel.org
Signed-off-by: Chris Li <chrisl@kernel.org>
Acked-by: Kairui Song <kasong@tencent.com>
Acked-by: Barry Song <baohua@kernel.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Chris Li

MAINTAINERS

@@ -16498,12 +16498,12 @@ F:	mm/secretmem.c
 
 MEMORY MANAGEMENT - SWAP
 M:	Andrew Morton <akpm@linux-foundation.org>
+M:	Chris Li <chrisl@kernel.org>
+M:	Kairui Song <kasong@tencent.com>
 R:	Kemeng Shi <shikemeng@huaweicloud.com>
-R:	Kairui Song <kasong@tencent.com>
 R:	Nhat Pham <nphamcs@gmail.com>
 R:	Baoquan He <bhe@redhat.com>
 R:	Barry Song <baohua@kernel.org>
-R:	Chris Li <chrisl@kernel.org>
 L:	linux-mm@kvack.org
 S:	Maintained
 F:	Documentation/mm/swap-table.rst