misc(root): Add support for Docker install

[notleanbarba]

Summary

Just a Docker image for React Email (https://github.com/notleanbarba/react-email-docker). It is useful to have a Docker container that you can configure directly in your project repo instead of installing it locally.

Benefits

• Auto refresh email template directly from project repo.
• Don't blow up project bundle size.
• Quick start for new projects.
• Easily integrate with development workflow using Docker compose.