Update datatype mapping document to reflect support array/nested row type for paimon

[luoyuxia]

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Description

as title.
https://fluss.apache.org/docs/streaming-lakehouse/integrate-data-lakes/paimon/#data-type-mapping
since array & nested row is supported, we should update document to reflect the support.

Willingness to contribute

• I'm willing to submit a PR!

[Jackeyzhe]

@luoyuxia Hi, I'd like to work on it, can you assign it to me?

[Jackeyzhe]

Hi @luoyuxia , I see there are no definitions of array & row in https://fluss.apache.org/docs/table-design/data-types/
Is there any issue tracking on it? If not, shall I update it together?