doc: Updated the react-native quickstart

[subhankarmaiti]

This PR refactors the existing quickstart for the React Native and Expo using react-native-auth0 SDK.

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not the default branch

[github-actions]

Summary

Status	Count
🔍 Total	8
✅ Successful	6
⏳ Timeouts	0
🔀 Redirected	2
👻 Excluded	0
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Redirects per input

Redirects in main/docs/quickstart/native/react-native-expo/index.mdx

• [200] https://auth0.com/docs/ | Redirect: Followed 1 redirect resolving to the final status of: OK. Redirects: https://auth0.com/docs/ --> https://auth0.com/docs

Redirects in main/docs/quickstart/native/react-native/index.mdx

• [200] https://auth0.com/docs/ | Redirect: Followed 1 redirect resolving to the final status of: OK. Redirects: https://auth0.com/docs/ --> https://auth0.com/docs
  Full Github Actions output