doc: modified usage in README.md and doc comment

[sttk]

Add forgotten code defer data.Close().

[Copilot]

Pull Request Overview

This PR adds the missing defer data.Close() call to code examples in documentation to ensure proper resource cleanup. The change corrects the sample code by adding the deferred Close() call immediately after creating a DataHub instance.

• Adds defer data.Close() to sample code in both documentation files
• Ensures proper resource management pattern is demonstrated in examples

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
doc.go	Adds defer Close() call to the DataHub usage example in code documentation
README.md	Adds defer Close() call to the DataHub usage example in the README

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