Update instructions for deploying Debezium on RHEL (downstream-only change)

The current instructions in the Debezium RHEL installation guide end come to an end with the step to start KC. They do not describe:

• How to register the connector
• How to verify that the connector creates topics and populates them with content from database.

Registering the connector
Add information about how to register the connector, by running a curl command against the KC REST API at localhost:8083/connectors, similar to the steps in the upstream DBZ tutorial
Specify the destination directory for saving plugin files: opt/kafka/connector-plugins/debezium-connector-<connector>/

Verifying the deployment
Add verification steps to check topic content as per upstream tutorial
E.g, run kafka-console-consumer.sh, as in Step 3 of the verification instructions for OCP, except that instead of running use `oc exec` to run it, you run it locally from /opt/kafka/bin/kafka-console-consumer.sh