Add screen_hint usage for login/signup in FAQ and fix usage in EXAMPLES.md

[subhankarmaiti]

This PR updates the documentation to improve clarity and accuracy around directing users to the login or signup screens using the screen_hint parameter.

Changes Included

• EXAMPLES.md

  • Wrapped login_hint and screen_hint inside the additionalParameters object, as required by the SDK.

• FAQ.md

  • Added a new question: "How can I prompt users to the login page versus signup page?"
  • Included sample login and signup functions using the correct usage of screen_hint inside authorize().

Why This Change?

• Clarifies a frequently asked use case—how to route users to specific authentication screens.
• Fixes potential confusion around parameter placement in authorize() options.
• Ensures documentation reflects the current SDK behavior.

Related Resources

• Auth0 API Docs – screen_hint