Update for Contributors library guidelines

[thomashoneyman]

This pull request is part of an effort to update and standardize the Contributors libraries according to the Library Guidelines. Specifically, it:

1. Adjusts the files and repository structure according to the repository structure section of the guidelines, which includes standard pr templates, issue templates, CI in GitHub Actions, ensures the project uses Spago, and so on.
2. Updates the README and documentation according to the documentation section of the guidelines. This is a first step towards ensuring Contributors libraries have adequate module documentation, READMEs, a docs directory, and tests (even if just usage examples) in a test directory.

In this library's case, I've taken a few specific actions.

1. I moved the bulk of the README documentation into the docs directory and linked to it from the README, for parity with how all the other contrib-libraries are handling this.
2. I applied the standard eslint configuration, which caught a few issues.

This PR isn't intended to change the code whatsoever, just to make sure that this library is using the same configurations and processes as the other libraries in this organization. With that in mind, despite adding the eslint configuration, this configuration is currently disabled so that it can be evaluated separately in a followup PR.

[maxdeviant]

@thomashoneyman I'm wondering if we should suppress the eslint warnings for the purposes of this PR and then come back and remove the suppressions and fix the offending code in a separate PR?

[thomashoneyman]

That's a better idea. Thanks for the suggestion.