Docs: Add compose example using confluent-local docker image

[scprek]

Resolves /discussions/818

• Breaking change? (if so, please describe the impact and migration path for existing application instances)

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[scprek]

I couldn't find a way to "hack" docker compose to treat kafka0 interactions from the other services as localhost (the default env vars in the image). So I ended up just overriding all ENV vars that had localhost in it that were required for Kafka UI and init kafka topics to work.