Updated README.md and CONTRIBUTING.md

[IzabellaRaulin]

• Added section how to start work with Google Cloud Platform
• Added kubesnap installation guidance
• Added images to README.md
• Added sections: Contributing, License and Acknowledgements
• Removed outdated information
• Updated CONTRIBUTING.md (correction in tittle, fixing the link to kubesnap issues)

[marcin-krolik]

LGTM