[DOCS] [Roadmap] Move CCR Docs to ES Reference Guide

[jrodewig]

Currently, cross-cluster replication (CCR) documentation is located in the Stack Overview.

This relocates CCR documentation to the Elasticsearch Reference Guide.

Tasks

• Rename "Administering Elasticsearch" to "Set up Elasticsearch for high availability." ([DOCS] Add CCR docs to the Elasticsearch Reference Guide #45704)
• Add CCR documentation to Elasticsearch Refererence Guide with level offset. ([DOCS] Add CCR docs to the Elasticsearch Reference Guide #45704)
• Redirect anchor links in APM server docs ([docs] Update link for "ccr-overview-beats" anchor apm-server#2589)
• Redirect anchor links in Beats docs ([docs] Add redirect for "ccr-overview-beats" anchor link beats#13288)
• Redirect links in Kibana docs ([DOCS] Update CCR links kibana#44012)
• Remove CCR documentation from the Stack Overview. ([DOCS] Remove CCR docs from Stack Overview stack-docs#464)
• Increment headings for CCR docs and remove level offset. ([DOCS] Remove leveloffset for CCR docs #46818)

[elasticmachine]

Pinging @elastic/es-docs

[elasticmachine]

Pinging @elastic/es-distributed

[lcawl]

I think there are links that will need to be fixed here too: https://www.elastic.co/guide/en/kibana/master/working-remote-clusters.html

[jrodewig]

Thanks for catching that @lcawl. I updated the issue description and opened elastic/kibana#44012 to address.