fix: Remove unnecessary vertical scrollbar and improve the example with tab format in "Rendering Arrays with Specific Separators" section

[umsungjun]

Overview

This PR remove unnecessary vertical scrollbar and improve the example with tab format in "Rendering Arrays with Specific Separators" section

• Fixed the issue causing an unwanted vertical scrollbar to appear on the right side of the code block.
• Refactored the example code by separating without-react-simplikit.tsx and with-react-simplikit.tsx into tabs for better readability.

Before

After

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]

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

Comments suppressed due to low confidence (2)

src/docs/ko/intro.md:54

• Both code blocks within the code-group use the same file label 'without-react-simplikit.tsx'. If they are meant to demonstrate different examples (e.g., with and without simplikit), consider updating one of the labels for greater clarity.

```tsx [without-react-simplikit.tsx]

src/docs/en/intro.md:54

• Both code blocks within the code-group use the same file label 'without-react-simplikit.tsx'. If they are intended to represent different scenarios, consider updating one of the labels for improved clarity.

```tsx [without-react-simplikit.tsx]

[vercel]

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[seungrodotlee]

Initially, it was implemented as a toggle.

However, there was feedback that showing the before-and-after in a single view would better illustrate the code improvements.

Therefore, the current version of the view was selected.

[seungrodotlee]

By the way, I noticed that I should fix gradient in dark mode by this PR...
Thanks!

[umsungjun]

@seungrodotlee

Thank you very much for the valuable feedback.
However, considering consistency with other pages, I carefully wonder if separating the views into tabs—like the previous version—might be more appropriate.

[umsungjun]

Alternatively, would it be okay if I re-submit the PR with vertical titles instead?

[seungrodotlee]

I have fix SplitView component in #173
and want to hear your opion!