Create documentation for cross-cluster search

[tylersmalley]

Original PR: #11114
Elasticsearch Documentation: https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-cross-cluster-search.html

[tbragin]

Agreed, it would be useful to add some information on how to configure Kibana to take advantage of the new cross-cluster support in 5.5.

I would assume it would live somewhere in this section:
https://www.elastic.co/guide/en/kibana/5.5/tribe.html

Perhaps we can base it on an example such as this

[alexfrancoeur]

@tbragin @tylersmalley I think having it's own page makes sense. It would be nice to reference with a URL pointing to the new Cross Cluster Search page in both the index pattern management docs as well as the console docs.

I added a 5.5 label as I think it makes sense to introduce this documentation with the release. As I understand it, documentation updates are not necessarily tied to a release - this is more of a forcing function to get them in as soon as possible.

[alexfrancoeur]

@epixa @spalger is there any chance we can get some Kibana documentation on CCS for the 5.5 release?

[tbragin]

We should also mark it "beta" if Elasticsearch keeps their "beta" label for cross-cluster search in 5.5: https://www.elastic.co/guide/en/elasticsearch/reference/5.5/modules-cross-cluster-search.html

[epixa]

@alexfrancoeur I'm not sure why we'd specifically call out cross cluster search in the console docs since we don't call out any other Elasticsearch APIs in particular. I don't think the console docs should start regurgitating Elasticsearch API documentation.

[alexfrancoeur]

@epixa I wasn't thinking about API's here. A lot of customers have requested support for tribe in console to make requests across multiple clusters. Given the fact that CCS addresses this, I thought it would be nice to have a note that Console now supports multiple clusters with CCS.

[epixa]

@alexfrancoeur I hear that, but I think the right approach here is highlighting that distinction from the tribe docs itself, since this is a sort of special case for folks that have already experienced the pains of tribe in Kibana.

[epixa]

@spalger I assigned #12599 to you for review