docs(useMap): fix code block formatting

[guesung]

Overview

Fix code block formatting in useMap.md example.

Before the change, it's as shown in the first image below, and after the change, it's as shown in the second image

Checklist

• Did you write the test code?
• Have you run yarn run fix to format and lint the code and docs?
• Have you run yarn run test:coverage to make sure there is no uncovered line?
• Did you write the JSDoc?

[vercel]

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[Copilot]

Pull Request Overview

Fix the Markdown code block formatting in the useMap documentation example.

• Replaced incorrect quadruple backtick fence with a standard triple backtick fence.
• Ensured the import { useMap } line is included inside the code block.