Docs: Update install prompt to use npm create

[kylegach]

What I did

See title

Checklist for Contributors

Testing

Manual testing

N/A - docs-only change

The prompt itself was tested for efficacy.

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

Summary by CodeRabbit

• Documentation
  • Updated Storybook installation instructions across multiple documentation pages to reflect the latest recommended setup method.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: e934e530-9bde-4930-881d-cd83dfa96c4a

📥 Commits

Reviewing files that changed from the base of the PR and between aba75f8 and b180787.

📒 Files selected for processing (3)

• docs/_snippets/prompt-install-storybook.md
• docs/get-started/install.mdx
• docs/index.mdx

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📝 Walkthrough

Walkthrough

This PR updates the Storybook installation command across documentation files, replacing npx storybook@latest init with npm create storybook@latest in the reusable prompt snippet and all downstream install-related callouts.

Changes

Storybook Install Command Update

Layer / File(s)	Summary
Update Storybook install command across documentation docs/_snippets/prompt-install-storybook.md, docs/get-started/install.mdx, docs/index.mdx	Replace the documented Storybook installation command from npx storybook@latest init to npm create storybook@latest in the reusable prompt snippet and the install-related callouts on the getting-started and main index pages.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• storybookjs/storybook#34648: Both PRs modify the Storybook "Copy prompt"/install instruction content—especially docs/_snippets/prompt-install-storybook.md and related callouts—switching between npx storybook@latest init and npm create storybook@latest usage.
• storybookjs/storybook#33244: Both PRs adjust the "Install Storybook"/Get Started CTAs on the docs (notably docs/index.mdx and related install-callout copy) to change/restructure the Storybook install command/prompt text.

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}