fixup: add contributing section

Signed-off-by: Simon Schrottner <simon.schrottner@dynatrace.com>

Author: aepfli

CONTRIBUTING.md

@@ -21,6 +21,38 @@ If you think we might be out of date with the spec, you can check that by invoki
 
 If you're adding tests to cover something in the spec, use the `@Specification` annotation like you see throughout the test suites.
 
+## Code Styles
+
+### Overview
+Our project follows strict code formatting standards to maintain consistency and readability across the codebase. We use [Spotless](https://github.com/diffplug/spotless) integrated with the [Palantir Java Format](https://github.com/palantir/palantir-java-format) for code formatting.
+
+**Spotless** ensures that all code complies with the formatting rules automatically, reducing style-related issues during code reviews.
+
+### How to Format Your Code
+1. **Before Committing Changes:**
+   Run the Spotless plugin to format your code. This will apply the Palantir Java Format style:
+   ```bash
+   mvn spotless:apply
+   ```
+
+2. **Verify Formatting:**
+   To check if your code adheres to the style guidelines without making changes:
+   ```bash
+   mvn spotless:check
+   ```
+
+    - If this command fails, your code does not follow the required formatting. Use `mvn spotless:apply` to fix it.
+
+### CI/CD Integration
+Our Continuous Integration (CI) pipeline automatically checks code formatting using the Spotless plugin. Any code that does not pass the `spotless:check` step will cause the build to fail.
+
+### Best Practices
+- Regularly run `mvn spotless:apply` during your work to ensure your code remains aligned with the standards.
+- Configure your IDE (e.g., IntelliJ IDEA or Eclipse) to follow the Palantir Java format guidelines to reduce discrepancies during development.
+
+### Support
+If you encounter issues with code formatting, please raise a GitHub issue or contact the maintainers.
+
 ## End-to-End Tests
 
 The continuous integration runs a set of [gherkin e2e tests](https://github.com/open-feature/spec/blob/main/specification/assets/gherkin/evaluation.feature) using `InMemoryProvider`.