Add feature development guide for Studio app

[Chhunneng]

Provide instructions in apps/studio/docs/ for developers to add new features:

• Adding new pages or components
• Modifying existing functionality
• Following the folder structure (src/, src/components/, src/hooks/)

[KanavCode]

I can Add this Instructions in README.md File.
Assign me I'll do this

[AadityaBansal01]

Hi, I’d like to contribute to this issue. Could you please assign it to me and also label it with hacktoberfest?