MAINTAINERS: add missing files to mm page alloc section

There are a number of files within memory management which appear to be
most suitably placed within the page allocation section of MAINTAINERS and
are otherwise unassigned, so place these there.

Link: https://lkml.kernel.org/r/20250618105953.67630-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Brendan Jackman <jackmanb@google.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: lorenzo-stoakes

MAINTAINERS

@@ -15875,8 +15875,17 @@ F:	include/linux/compaction.h
 F:	include/linux/gfp.h
 F:	include/linux/page-isolation.h
 F:	mm/compaction.c
+F:	mm/debug_page_alloc.c
+F:	mm/fail_page_alloc.c
 F:	mm/page_alloc.c
+F:	mm/page_ext.c
+F:	mm/page_frag_cache.c
 F:	mm/page_isolation.c
+F:	mm/page_owner.c
+F:	mm/page_poison.c
+F:	mm/page_reporting.c
+F:	mm/show_mem.c
+F:	mm/shuffle.c
 
 MEMORY MANAGEMENT - RECLAIM
 M:	Andrew Morton <akpm@linux-foundation.org>