Documentation/sysctl/vm.txt: update numa_zonelist_order description

Documentation/sysctl/vm.txt: update numa_zonelist_order description

Commit 3193913ce62c ("mm: page_alloc: default node-ordering on 64-bit
NUMA, zone-ordering on 32-bit") changes the default value of
numa_zonelist_order.  Update the document.

Signed-off-by: Xishi Qiu <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Kamezawa Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>