Document the output of kubectl describe couchbasecluster

This section should be titled "Getting Details about a Couchbase Cluster".

It should also have a sample print out of the describe output of a cluster. It should discuss the spec section at a high level (we can link to the cluster spec overview if someone wants more details. The status section should be described in detail and the conditions and events sections should be discussed at a high level (with links provided to the conditionsAndEvents.md file for more details).