docs: add docs for signUp (local povider)

[Vijayabhaskar96]

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• [] 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This pull request updates the documentation and enhances the signUp function within our authentication module. Specifically, it:

• Adds detailed comments to the signUp function examples to clearly explain each use case.

The aim is to provide clearer guidance for developers on how to use the signUp function effectively and to offer improved functionality that caters to a wider range of application scenarios.

📝 Checklist

• [] I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.