OpenShift deployment instruction improvements

Multiple things should be improved in the OpenShift guide:

• Don't register connector via REST but via KafkaConnector CRD
• Don't hard code Strimzi Kafka version
• Use new deployment mode instead of manually creating an image
• In deployment, step 3, a step is missing after c, for actually deploying Kafka Connect based on that new image via Strimzi
• Image is broken/missing in step 3c
• In verifiying, step 3, it should say "# Message 1 Key" in the listing (doc has been changed, doesn't apply)
• Show how to source the user password from an environment variable

See the Strimzi blog which discusses the CRD part (and we do it in other parts of the docs, too).