This change adds GoDoc comments to many of the public symbols in the
`pkg/` directory. It also includes various improvements to the
documentation in `README.md` and other markdown files in the `docs/`
directory.
This is a partial documentation effort, as requested by the user, to
get a pull request submitted quickly.
Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
