docs: Added contributing section

Fixes #5899

Author: actions-user

README.md

@@ -83,3 +83,8 @@ For more information, see https://www.bis.doc.gov
 docker/cli is licensed under the Apache License, Version 2.0. See
 [LICENSE](https://github.com/docker/docker/blob/master/LICENSE) for the full
 license text.
+
+
+## Contributing
+
+Contributions are welcome! Please feel free to submit a Pull Request.