Interactive queries documentation

[clvacher]

Problem

Documentation on interactive queries does not showcase an actual implementation of an interactive query, leaving the users scratching their heads for it.

Suggestion

A detailled explanation on how to interact with a store in the README, at least mentioning the autowiring of the KafkaStreamsInitializer class to retrieve the kafkaStreams instance

A link to a side project (?) showcasing the feature

Additional Context

Integrating @loicgreffier 's work on the subject for internal showcases to Kstreamplify is probably a very good addition to the library.

[loicgreffier]

Linked with #141

[loicgreffier]

I definitely think that accessing the kafka streams instance should have its own documentation part in the Getting Started section as it can be use for multiple purposes, not only interactive queries. Like :

• Getting Started
  ...
  • Error Handling
    • Topology
    • Production and Deserialization
    • Avro Schema
  • REST Endpoints
  • Accessing the Kafka Streams instance

With this kind of code sample:

public class MyService {
    @Autowired
    private KafkaStreamsInitializer kafkaStreamsInitializer;

    public void doSomething() {
      kafkaStreamsInitializer.getKafkaStreams();
    }
}

[loicgreffier]

Initialized by #204