Enhance Consumer and Producer Documentation with More Practical Examples

I noticed that users frequently ask questions about basic usage patterns for producer and consumer in kafka-python.

The aiokafka project provides detailed usage examples that are helpful for understanding:

Consumer group usage

Manual commit vs auto commit

Async message handling

Error handling patterns

I propose enhancing kafka-python documentation by:

Adding more practical producer examples

Adding consumer group examples

Adding error handling and retry examples

Providing clearer configuration explanations

This would reduce repeated user questions and improve onboarding experience.