Update according to Contributors library guidelines

[maxdeviant]

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, automatic stale issue management, 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.
3. Updates labels where relevant to help folks better sift through issues on this library and get started contributing.

This PR is the groundwork for followup efforts to ensure contributor libraries are kept up-to-date, documented, tested, and accessible to users and new contributors.

[maxdeviant]

Verified that spago build and spago test are working:

λ spago build
[info] Installation complete.
[info] Build succeeded.
λ spago test
[info] Installation complete.
[info] Build succeeded.
[info] Tests succeeded.

I also tried out to the two existing npm scripts (npm run test:browser and npm run test:serve) and these both seemed to work.

[thomashoneyman]

Mind deleting the lockfile?

[maxdeviant]

Lockfile has been removed and added to .gitignore.