correct the link to nginx.yaml for flexvolume
correct the link to nginx.yaml for flexvolume

Signed-off-by: yanxuean <fea65f46f148dc221c24d094de388690c66eb375@zte.com.cn>

kubernetes/community,pwittrock/community,kubernetes/community,bgrant0607/community,kubernetes/community,pwittrock/community,bgrant0607/community