docs: update code example and some contents

[jsparkdev]

Overview

• add missing inline code
• rename state update function
• update unnatural Korean translation

Checklist

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

[Copilot]

Pull Request Overview

This PR updates the introductory documentation in both English and Korean to improve clarity and consistency. Key changes include:

• Adding missing inline code formatting around "react-simplikit".
• Renaming the state update function from setOpen to setIsOpen.
• Updating the Korean translation for a more natural tone.

Reviewed Changes

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

File	Description
src/docs/ko/intro.md	Updated code sample naming and refined translation.
src/docs/en/intro.md	Updated inline code formatting and naming convention.

[seungrodotlee]

How about keep setOpen?

[jsparkdev]

@seungrodotlee

Thanks for good review.

I've fixed it to be consistent with the state names used on other page.

If this was the intent, I'll leave setOpen as is.

[seungrodotlee]

Oh, I missed that — thanks for pointing it out.
It might be a good idea to review the naming style in the example code.
Personally, I find the set* format more intuitive than setIs*.

Would you mind unifying the naming style in this PR accordingly?

[seungrodotlee]

Thanks! 👍