release-8.1: update pingcap.com ZH and CN links#21140

qiancai wants to merge 3 commits intopingcap:release-8.1pingcap/docs-cn:release-8.1from

qiancai:v8.1/repace-cn-zh-linksqiancai/docs-cn:v8.1/repace-cn-zh-linksCopy head branch name to clipboard