[8.x](backport #4777) Add OTel quickstart to Get started page (#4780)

* Add OTel quickstart to Get started page (#4777)

(cherry picked from commit 20b43cb)

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Co-authored-by: Mike Birnstiehl <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

docs/en/observability/observability-get-started.asciidoc

@@ -54,6 +54,7 @@ Follow the steps in these guides to get started quickly:
 
 * <<quickstart-monitor-hosts-with-elastic-agent>>
 * <<monitor-k8s-logs-metrics-with-elastic-agent>>
+* <<quickstart-monitor-hosts-with-otel>>
 * <<monitor-k8s-otel-edot>>
 * <<collect-data-with-aws-firehose>>