📝 add contributing guide (issue #83)

Author: EmanuelSommer

CONTRIBUTING.md

@@ -0,0 +1,43 @@
+# Contributing to bde
+
+Thanks for your interest in improving `bde`. We welcome bug reports,
+documentation fixes, examples, tests, and focused code contributions.
+
+Please use GitHub as the default place for project communication:
+
+- Issues: https://github.com/scikit-learn-contrib/bde/issues
+- Pull requests: https://github.com/scikit-learn-contrib/bde/pulls
+
+## Contributing changes
+
+For small fixes, open a pull request directly. For larger changes or API changes,
+please open an issue first so the approach can be discussed.
+
+Recommended workflow:
+
+1. Fork the repository.
+2. Create a branch for your change.
+3. Install the development environment as outlined in the README and do not forget to also install the `pre-commit` hooks.
+4. Add tests or documentation when relevant.
+5. Run the relevant checks (lint,tests).
+6. Open a pull request on GitHub and link any related issue.
+
+## Reporting issues
+
+Please report bugs, feature requests, and documentation problems through GitHub
+Issues. Before opening a new issue, check whether a similar issue already exists.
+
+For bug reports, include:
+
+- A minimal reproducible example.
+- The full traceback or error message.
+- Your operating system, Python version, and relevant package versions.
+- The expected behavior and the behavior you observed.
+
+## Seeking support
+
+Please use GitHub Issues for usage questions and support requests. This keeps
+answers visible to other users and helps the project maintain a searchable record.
+
+Direct email to the maintainers should be reserved for rare cases that are not
+appropriate for a public GitHub issue, such as sensitive or private matters.