add another asyncapi document to work against

we have https://github.com/derberg/python-mqtt-client-template/blob/main/test/fixtures/asyncapi.yml

but would make sense to have another completely different example we could test against, to make sure that template have no assumptions and is really agnostic

maybe https://github.com/asyncapi/spec/blob/master/examples/streetlights-mqtt-asyncapi.yml 🤔 