fix copilot-exercises to use IntelliJ features

[EficodeRjpalt]

The Copilot-Exercises instructions currently do not fully reflect the capabilities and workflows available in IntelliJ IDEA. Please update the instructions to:

• Align all steps and guidance with IntelliJ IDEA's built-in Copilot features and user experience.
• Remove or revise any content that is specific to other IDEs or not relevant for IntelliJ users.
• Ensure the instructions are clear, concise, and tailored for developers using IntelliJ IDEA.
• Add practical examples or tips that leverage IntelliJ's Copilot integration where appropriate.

This update will help users get the most out of Copilot within the IntelliJ environment and ensure the documentation is accurate and helpful.