mjermann

modified version of #29 for testing

Implement method to see the available topics for an instantiated `KafkaBroker`.

Add roxygen documentation to `KafkaBroker`, `KafkaConsumer`, and `KafkaBroker` R6 objects detailing the methods and arguments.

This project should have some guidelines for making contributions and discussing on issues and PRs. Example: https://help.github.com/en/articles/setting-guidelines-for-repository-contributors