Add docs to configure remote ES output

[kilfoyle]

Previously, the steps to configure a remote Elasticsearch output were documented in the "Agent Monitoring" section of the docs, since I thought only monitoring data was supported.

Since both integrations and monitoring data are now supported, I've made a new Remote Elasticsearch Output page.

Please see previews:

• New Remote Elasticsearch Output page
• Updated Send Elastic Agent monitoring data to a remote Elasticsearch cluster section

Closes: #848
Closes: #759

[github-actions]

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[juliaElastic]

LGTM

[amyjtechwriter]

LGTM