MAINTAINERS: add mm swap section

MAINTAINERS: add mm swap section

In furtherance of ongoing efforts to ensure people are aware of who
de-facto maintains/has an interest in specific parts of mm, as well trying
to avoid get_maintainers.pl listing only Andrew and the mailing list for
mm files - establish a swap memory management section and add relevant
maintainers/reviewers.

Link: https://lkml.kernel.org/r/20250604163139.126630-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: Kairui Song <kasong@tencent.com>
Acked-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Barry Song <baohua@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>