Update IntelliJ/Android Studio Setup Docs in README (Outdated Video & Steps)

Hi Flutter team 👋

First of all, thank you for all the amazing work you’re doing for the community! 🚀

I noticed that the **IntelliJ/Android Studio setup documentation in the README, as well as the linked video guide, are quite outdated** — they appear to be based on very old versions of Android Studio.

For newcomers, this can be a bit confusing since the UI, menus, and setup flow have changed significantly in recent releases.

👉 It would be super helpful to update both the **written documentation** in the README and the **video/screenshots** with instructions from the latest versions. This would make the onboarding process much smoother and more beginner-friendly.

I’d be glad to help test or review updated instructions if needed. 💡

Thanks again for keeping Flutter awesome! 💙