add Ruoyu as a subsystem maintainer of zookeeper components

Ruoyu is an active developer and heavy user of sheepdog. His clusters
are deployed with zookeeper so he often solves problems related to the
software. I'd like him to be a subsystem maintainer of zookeeper
components for improving our development speed.

(This patch also fixes invalid description in the file which was
introduced in a past commit)

Cc: Ruoyu <liangry@ucweb.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
dog: read the latest epoch is enough in cluster_alter_copy

Because the purpose is to get the copy policy and the number of
copies only, reading the latest epoch is nice. No need to read
all epoch records.

Signed-off-by: Ruoyu <liangry@ucweb.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Fix comment errors

Signed-off-by: Bingpeng Zhu <nkuzbp@foxmail.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>