fix: update package installation instructions in README files

[rahimn20]

• Updated npm, Yarn, and pnpm installation commands in both README.md and README.kr.md to use @dongminyu/react-native-step-counter instead of react-native-step-counter.

🔍 Summary

Please provide a concise description of what this PR does and why.

• What did you change?
  Corrected the install commands in both English and Korean READMEs to use the correct scoped package name: @dongminyu/react-native-step-counter.
• Why is this change necessary?
  The previous instructions used react-native-step-counter, which does not exist on the npm registry and results in 404 errors during installation. Updating it to the correct package name prevents installation issues for users.

🛠️ Changes

• Updated README.md and README.kr.md:
  • Changed npm install react-native-step-counter → npm install @dongminyu/react-native-step-counter
  • Changed yarn add react-native-step-counter → yarn add @dongminyu/react-native-step-counter
  • Changed pnpm add react-native-step-counter → pnpm add @dongminyu/react-native-step-counter

🔗 Related Issue

• Closes #__

✅ Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (backwards-incompatible)
• Documentation update
• Chore / Refactoring

📋 Checklist

• My code follows the repository’s style guidelines
• I have added tests covering my changes
• I have run yarn lint and yarn test locally with no failures
• I have updated the README or relevant documentation
• I have provided version and environment details if applicable

🚀 How to Test

1. Use any of the following commands:

   npm install @dongminyu/react-native-step-counter
   yarn add @dongminyu/react-native-step-counter
   pnpm add @dongminyu/react-native-step-counter

2. Installation should succeed without 404 errors.
3. Previously, running:
   yarn add react-native-step-counter
   resulted in:

   ➤ YN0027: react-native-step-counter@unknown can't be resolved to a satisfying range
   ➤ YN0035: Package not found
   ➤ YN0035:   Response Code: 404 (Not Found)
   ➤ YN0035:   Request Method: GET
   ➤ YN0035:   Request URL: https://registry.yarnpkg.com/react-native-step-counter
   

📸 Screenshots (if applicable)

If your change adds UI or visual output, include before/after screenshots or GIFs.

[trunk-io]

Merging to main in this repository is managed by Trunk.

• To merge this pull request, check the box to the left or comment /trunk merge below.