[develop activities] misunderstand of replica in topology.yaml

[ilixiaocui]

https://github.com/opencurve/curveadm/wiki/topology#replica

Maybe it's better to use instances or servicenum instead of replica.

[zhanghuidinah]

• This issue has been chosen for community developer activities. Welcome to feel free to try it. After the PR is merged, you will receive a gift package and a certificate as a community contributor.

• Developer Activities Registration Steps please ref [2023 Q2 Developer Activities]: Call For Participation！ curve#2334 (comment)

[tiansuo114]

I want to assign this issue

[caoxianfei1]

I want to assign this issue

done