docs: add contributing guidelines and Renovate configuration

- Created a new `CONTRIBUTING.md` file to outline contribution guidelines, including setup instructions, development workflow, and commit message conventions.
- Introduced a `renovate.json5` file to configure Renovate for dependency management, detailing strategies for updates, automerging, and security practices.
- Enhanced documentation to improve clarity and support for contributors, ensuring a streamlined onboarding process.

Author: kzndotsh