docs: add redis prerequisite for Caching Module

[shahednasser]

Summary

What — What changes are introduced in this PR?

Closes DX-2298

Why — Why are these changes relevant or necessary?

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How — How have these changes been implemented?

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Testing — How have these changes been tested, or how can the reviewer test the feature?

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Examples

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// Example usage

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Checklist

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Additional Context

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Latest commit: 4c76ad2

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Project	Deployment	Preview	Comments	Updated (UTC)
api-reference	Building	Preview	Comment	Nov 14, 2025 2:23pm
resources-docs	Ready	Preview	Comment	Nov 14, 2025 2:23pm

6 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
api-reference-v2	Ignored	Preview		Nov 14, 2025 2:23pm
cloud-docs	Ignored	Preview		Nov 14, 2025 2:23pm
docs-ui	Ignored	Preview		Nov 14, 2025 2:23pm
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