Fix apibase (stulzq#43)

* 🐛 set `api_base=/v1` as default value

* 🐛 fix EndpointUrl=nil when `InitFromEnvironmentVariables`

* ✨ add notebook examples

* 💚 fix ci err, fmt for log.Fatalf

fix: CORS

fix: OPTIONS req err

chore: add release full changelog

chore: update goreleaser

feat: update readme

feat: add doc img