Suggestion: Make images available on Docker Hub

Thank you for the work on this project, it looks like a great solution to running Cron in a secure containerised environment.

I'd like to suggest that this project provide images on Docker Hub. The main advantage I see to doing this would be that for using Supercronic in a project, I could simply use the `COPY` directive in my Dockerfile to copy the binary from the most appropriate Supercronic image.

For example, the PHP Composer project does this and in a Dockerfile I simply need to include the following:
```COPY --from=composer:2 /usr/bin/composer /usr/bin/composer```

This line ensures that I always have the most up to date build of Composer 2 in my final image, and (while not applicable to Composer) Docker would know which architecture I need, making my Dockerfile more portable across different architectures (x86, ARM, etc).

Thanks,
-Aaron

The issue names no repository files or tests; start by reviewing the project's current Docker and release setup. Determine how images could be published to Docker Hub for the supported architectures and usable with Dockerfile COPY --from; done means users can reference maintained Supercronic images without building them locally.

Written by the indexing model from the issue text.