Create a documentation index and reflect it on the website

[oscerd]

We can collect possible index here and then create the index in the docs. So it will be more clear where to look for something.

[oscerd]

[[CamelKafkaConnector-index]]
= Apache Camel Kafka Connector

• xref:about.adoc[What is it?]
• xref:getting-started.adoc[Getting started]
  ** xref:try-it-out-locally.adoc[Try it locally]
  ** xref:try-it-out-on-openshift-with-strimzi.adoc[Try it on OpenShift cluster]
  ** xref:getting-started-with-packages.adoc[Packages documentation]

For beginning.