Evaluate the potential of `go generate` + automation

From #200

### Potential of `go generate` + automation

Can we leverage the potential of `go generate` + automation to provide more quality to this library? Things that come into my mind:

- Updating API URLs
- Generating structs + data structures for API responses + API requests (e.g. options)
- Keeping API endpoints up to date (or maybe providing a list of API endpoints we support + not supports (and where help is needed)).

google/go-github is using this and might be an inspiration. See
- [go-github/github/gen-accessors.go](https://github.com/google/go-github/blob/0573e88402f1db392537e0cbb2c79f1c03d1c6a0/github/gen-accessors.go)
- [go-github/github/gen-stringify-test.go](https://github.com/google/go-github/blob/0573e88402f1db392537e0cbb2c79f1c03d1c6a0/github/gen-stringify-test.go)
- [go-github/update-urls](https://github.com/google/go-github/tree/master/update-urls)
- [Go generate should validate and fix all documentation URLs #1476](https://github.com/google/go-github/issues/1476)
- [go generate in CONTRIBUTING.md](https://github.com/google/go-github/blob/master/CONTRIBUTING.md#submitting-a-patch)