Add Kibana documentation

[barkbay]

Fix #1389

[charith-elastic]

This is very comprehensive. 👍 I have made some suggestions to fix links and change wording to comply with the Elastic style guide.

[anyasabo]

LGTM, a couple of nits. Another thing I realized we might want to call out is how to connect to an external cluster, e.g.
#1875 (comment)

because it's easy to configure it insecurely (for instance, putting the ES password in the Kibana spec rather than a secret), so it would be helpful to give people a clear and secure example

[barkbay]

LGTM, a couple of nits. Another thing I realized we might want to call out is how to connect to an external cluster, e.g.
#1875 (comment)

because it's easy to configure it insecurely (for instance, putting the ES password in the Kibana spec rather than a secret), so it would be helpful to give people a clear and secure example

👍 , and this is what I wanted to do at first when I realized that user must provide a reference to an Elasticsearch cluster. I'm not sure it makes sense to talk about that until #1875 is resolved.

[alaudazzi]

Left some minor comments, otherwise LGTM.