Add note about NEXT_DATA hydration

[MaedahBatool]

Missing documentation around NEXT_DATA hydration when using getServerSideProps(). This PR warn users that the result of getServerSideProps()/getStaticProps is also available on the client-side due to React Hydration so they should not use any sensitive information in the props.

Bug

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Feature

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• Documentation added
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Documentation / Examples

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[ijjk]

I think we can expand on this and potentially have a separate section specifically about hydration although this seems like a good initial note to have, thanks!

[MaedahBatool]

I think we can expand on this and potentially have a separate section specifically about hydration although this seems like a good initial note to have, thanks!

Yes, that's a nice idea. We can def. work something around this.

[leerob]

Let's keep the format consistent with other notes. Note:

I think we can drop "that irrespective of rendering type"

Note:* Any props returned in getInitialProps will be passed to the...

"Make sure that you don't pass any" to just "Don't pass any..."