docs: update README with CI and publishing details

- Added section on CI processes, including unit tests and E2E test conditions.
- Documented the PyPI publishing workflow and local packaging script usage.

Author: funkatron

README.md

@@ -146,3 +146,10 @@ License
 -------
 
 This project is licensed under the MIT License. See the [LICENSE](LICENSE) file for details.
+
+CI & Publishing
+---------------
+
+- CI runs unit tests and linting on every push. E2E tests run if `GEOCODIO_API_KEY` is set as a secret.
+- PyPI publishing workflow supports both TestPyPI and PyPI. See `.github/workflows/publish.yml`.
+- Use `test_pypi_release.py` for local packaging and dry-run upload.