docs: update dynamic form item demo

[kovsu]

并且这个判断有逻辑问题，当 dynamicValidateForm.domains.length 不为 1 的时候都被带上了 disabled 属性，并且 disabled 没有任何作用，依然可以点击。

There is a logic issue here. When dynamicValidateForm.domains.length is not equal to 1, the component receives the disabled property. Furthermore, the disable property seems to serve no purpose, as you can also trigger a click event.

[github-actions]

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