Update CONTRIBUTING.md with coverage suggestion (#180)

Author: enoodle

CONTRIBUTING.md

@@ -32,6 +32,7 @@ Help us keep the docs clear and useful by fixing typos, updating outdated inform
 - Make Changes – Keep your commits small, focused, and well-documented. For detailed build and test instructions, refer to [Building from Source](docs/developer/building-from-source.md).
 - Log Changes – For behavior-affecting changes (features, fixes, API changes), update the [changelog](CHANGELOG.md) file under the "Unreleased" section. Follow the format at [keepachangelog.com](https://keepachangelog.com/en/1.1.0/). Skip logging internal changes like refactoring or tests.
 - Submit a PR – Open a pull request and reference any relevant issues or discussions.
+- Coverage - Please look at the coverage change details and create unit tests, integration tests or end-to-end tests to cover new functionality or changes.
 
 ### Pull Request Checklist
 Before introducing major changes, we strongly recommend opening a PR that outlines your proposed design.