Improve charmodelling README with setup instructions and usage guide

[NA-V10]

What changes were proposed in this pull request?

This pull request improves the charmodelling README by making it easier for beginners to understand and run the example.

Changes include:

• Added prerequisites section
• Added quick start instructions
• Added main classes overview
• Added run commands with Maven examples
• Added expected output section
• Reorganized content for better readability

How was this patch tested?

This patch was tested manually by:

• Verifying markdown formatting and heading structure
• Checking that all code blocks render correctly
• Confirming Maven commands match the existing package structure
• Reviewing links and section ordering for readability
• Previewing the README to ensure proper formatting on GitHub