chore(website): add notice on timestamp field renaming in the Elasticsearch sink, when use data_stream mode

[up2neck]

Summary

Elasticsearch sink documentation doesn't highlight data_stream mode behavior on .timestamp field.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

• Please read our Vector contributor resources.
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    • cargo clippy --workspace --all-targets -- -D warnings
    • cargo nextest run --workspace (alternatively, you can run cargo test --all)
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References

[bits-bot]

All committers have signed the CLA.

[maycmlee]

Just a small editorial edit.

[up2neck]

@maycmlee @pront
Synched my branch with the master.

[up2neck]

@pront
Seems like automatic merge doesn't work because it expects for changelog to be updated, does it?

[pront]

@pront Seems like automatic merge doesn't work because it expects for changelog to be updated, does it?

Updated labels and approved check run 🚀

[up2neck]

@pront
Unfortunately there was trailing whitespace :) It requires your approval again