Add IntelliJ setup instructions (Windows)

[koushikkothagal]

Add IntelliJ setup instructions here: https://github.com/koushikkothagal/java-backend-bootcamp/tree/main/session-02-big-picture#setting-up-intellij

Add step-by-step instructions and screenshots. Submit a PR when done

[pratiknayak28]

I want to take this up, please assign it to me.

[koushikkothagal]

All yours! Thanks