[meta] Improve Fleet Server doc experience

[dedemorton]

Description

We've documented the basic steps for users who need to deploy Fleet Server, but users need more guidance.

Related issues and PRs:

• Document Fleet Server configuration settings #642
  PR in review: https://www.elastic.co/guide/en/fleet/current/fleet-server.html#fleet-server-configuration
• Fleet Server scaling and deployment guidelines #523
  PR in review: Add Fleet Server deployment and scaling docs #1061
• Fleet server production mode certs #1007
  PR in review: Update Fleet Server docs to include production mode option #1091

Collaboration

TBD

• The docs team will lead producing the content
• The product team will provide the initial content and the docs team will edit / review
• The docs team will define with product team the structure and location, and the product team will provide the initial content
• Other (please describe)

Contact Person:

TBD

Suggested Target Release

TBD

Stakeholders

@elastic/obs-docs
@mostlyjason
@nimarezainia

[dedemorton]

Closing because we've done all the tasks in the list. I'm not saying we shouldn't do more work, but let's come up with a new meta issue.