Describe the new kernel.org location of the MM trees.
Suggested-by: NDavid Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>