docs: the ClusterEviction plugin was not add to the document

[Vacant2333]

Task description:
https://github.com/karmada-io/website/blob/main/docs/developers/customize-karmada-scheduler.md?plain=1#L18
the ClusterEviction plugin was not add to the document

Solution:
find out that what the plugin do, and update the en and zh-ch docs

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[seanlaii]

/assign

[XiShanYongYe-Chang]

Hi @seanlaii, you may send a PR in the website repo.

If you encounter any problems during the modification, you can give us feedback in the comments.

[XiShanYongYe-Chang]

Hi @Vacant2333 can you help take a review for karmada-io/website#588