This file collects all the interfaces specific to Alibaba Cloud Kernel.

Add "memory.wmark_min_adj", "memory.exstat", and "zombie memcgs reaper"
descriptions.
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NGavin Shan <shan.gavin@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>