add contributing to readme

Author: hjgraca

README.md

@@ -57,6 +57,13 @@ Not using .NET? No problem, we have you covered. Here are the other members of t
 * Structured logging initial implementation from [aws-lambda-logging](https://gitlab.com/hadrien/aws_lambda_logging)
 * Powertools idea [DAZN Powertools](https://github.com/getndazn/dazn-lambda-powertools/)
 
+## 👋 Contributing
+
+We welcome contributions from developers of all levels to our open-source project on GitHub. If you'd like to contribute, please check our contributing guidelines and help make this project more accessible.
+
+
+[![Star History Chart](https://api.star-history.com/svg?repos=awslabs/aws-lambda-powertools-dotnet&type=Date)](https://star-history.com/#awslabs/aws-lambda-powertools-dotnet&Date)
+
 ## Connect
 
 * **AWS Lambda Powertools on Discord**: `#dotnet` - **[Invite link](https://discord.gg/B8zZKbbyET)**