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>

Author: lorenzo-stoakes

MAINTAINERS

@@ -15816,6 +15816,25 @@ S:	Maintained
 F:	include/linux/secretmem.h
 F:	mm/secretmem.c
 
+MEMORY MANAGEMENT - SWAP
+M:	Andrew Morton <akpm@linux-foundation.org>
+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:	include/linux/swap.h
+F:	include/linux/swapfile.h
+F:	include/linux/swapops.h
+F:	mm/page_io.c
+F:	mm/swap.c
+F:	mm/swap.h
+F:	mm/swap_state.c
+F:	mm/swapfile.c
+
 MEMORY MANAGEMENT - THP (TRANSPARENT HUGE PAGE)
 M:	Andrew Morton <akpm@linux-foundation.org>
 M:	David Hildenbrand <david@redhat.com>