docs: update broken links for apm-guide-ref #1385

[ollyhowell]

Links updated as per elastic/observability-docs#1385. The old links will break when 7.17 releases. This PR and all backports must be merged before the 7.17 release. Thanks!

Backports

• 3.x: [3.x] Doc link fixes #2542

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• Start Time: 2022-01-20T18:07:31.391+0000

• Duration: 4 min 32 sec

• Commit: 112bb46

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[bmorelli25]

Thanks, Olly! LG. I'll tag the Node.js team for review and create the lone backport.

[trentm]

elastic/observability-docs#1385 suggests this one should be "Remove from Node.js Agent"?

[bmorelli25]

That was an incorrect assumption on my part. This config variable is still valid for the standalone method of running APM Server. We'll need to remove this at a later date.

[trentm]

elastic/observability-docs#1385 says

{apm-server-ref}/intake-api.html -> {apm-guide-ref}/api.html

Though perhaps for this one we'd (eventually?) want https://www.elastic.co/guide/en/apm/guide/7.17/api-events.html ? I'm not sure if the intent of this PR is to just fix the {apm-server-ref-v} reference, or to also change from the "Legacy APM Server Reference" to the new Agent-based APM server docs.

[bmorelli25]

Unfortunately, the goal here is just to fix the outdated {apm-server-ref-v} refs. There are improvements that could be made to all of the agent docs to better differentiate between running APM Server in standalone mode vs the APM integration, but I don't have the bandwidth to tackle those right now.

As for the API link. It looks like this was a mistake, but I'd agree that the current link is better than what I had proposed in elastic/observability-docs#1385.