Duplicated content related with configuring APM server and settings

[eedugon]

The following files feel very similar and with duplicate information. It should be addressed and fixed at some point:

• reference/apm/cloud/apm-settings.md
• solutions/observability/apm/configure-apm-server.md

IMO the reference content apm-settings shouldn't probably have the narrative explanations about how to configure the APM server, and provide only the reference of the settings.

On the other hand the configure-apm-server.md feels much more complete and with more settings, but a lot of them appear to be duplicated.

There are two options here:

• Leave all the info in the solution doc
• Move all settings to the reference content and avoid duplicating the list of settings

[florent-leborgne]

I believe there are PRs currently open to update these files stating similar ideas (though not actually deduplicating). I'd move settings to reference docs to be consistent with the philosophy of the new docs, and link to it from the other places.