Create a `CONTRIBUTING.md` guide

[hiltontj]

The repository should have a contributing guide, which can help future contributors understand some of the following:

• Pull Request and Release process
• How to use tracing and test_log crates in serde_json_path to debug queries and tests
• Overview of the workspace structure and what code resides where
• Conduct / Rust Code of Conduct
• How to submit bugs / file issues