[8.16] Update fleet-settings.asciidoc (elastic#203194) (elastic#206414)

# Backport

This will backport the following commits from `main` to `8.16`:
- [Update fleet-settings.asciidoc
(elastic#203194)](elastic#203194)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

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Co-authored-by: Michael Bischoff <[email protected]>

docs/settings/fleet-settings.asciidoc

@@ -112,6 +112,8 @@ List of agent policies that are configured when the {fleet} app starts.
     ID of the output to send data. (Need to be identical to `monitoring_output_id`)
   `monitoring_output_id`::: 
     ID of the output to send monitoring data. (Need to be identical to `data_output_id`)
+  `fleet_server_host_id`:::
+    ID of the fleet server.
   `package_policies`::: 
     List of integration policies to add to this policy.
 +