Consider adding a CONTRIBUTING.md file

As a new contributor it would be very helpful to have some guidance around the expectations for committing code.

Here's a reference for creating one: https://mozillascience.github.io/working-open-workshop/contributing/.

Start by reviewing the repository root and the linked contributing-guide reference. Add a CONTRIBUTING.md that explains the project's expectations for committing code and contributing, with completion defined by the new guidance being present and readable.

Written by the indexing model from the issue text.