Fix typo in docs for derivative function

[zacklitzsinger]

Fixed typo in docs for derivative function.

time_inerval -> time_interval

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:white_check_mark: yihaoDeng
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:x: zacklitzsinger

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[guanshengliang]

很久没有看 github 仓库，今天注意到您的这个 PR。 由于时间较长，这段时间的分支变化导致出现了代码冲突。我 cherry pick 您的 commit (82885a54eb83d089b7c09562f74d59d6559502d3)，重新提了 PR(https://github.com/taosdata/TDengine/pull/28573) 且已经合并。 因此关闭当前 PR。

非常感谢您的支持