Fixed nav with basic concepts
* xref:about.adoc[What is it?]
+** xref:basic-concepts.adoc[Basic concepts]
* 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]
