[zh-cn] Move what-is-kubernetes to overview page

[windsonsea]

Perform this move action by en upstream #35298, which may need some time to check:

• Relocating
• Text update

content/zh-cn/_index.html
ontent/zh-cn/docs/concepts/overview/_index.md
content/zh-cn/docs/concepts/overview/components.md
content/zh-cn/docs/concepts/overview/what-is-kubernetes.md

Preview: https://deploy-preview-36182--kubernetes-io-main-staging.netlify.app/zh-cn/docs/concepts/overview/

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[tengqm]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tengqm

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• content/zh-cn/OWNERS [tengqm]

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[yanrongshi]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: f84d571cc4dddc5db6bac2a63360fa6e1c313908