update fleet guide link to current

Author: colleenmcginnis

docs/en/observability/apm/monitor-apm-server/monitor.asciidoc

@@ -29,9 +29,8 @@ Alternatively, open the **{stack-monitor-app}** app in {kib} and follow the in-p
 *Only use this option if you have _not_ yet enrolled {agent}.*
 If you edit and re-enroll {agent}, you will likely lose the state of the agent.
 
-If you have already enrolled the {agent}, consider using the Fleet UI to change the
-HTTP monitoring port of the agent using the processed outlined in
-{fleet-guide}/agent-policy.html#agent-policy-http-monitoring[Override the default monitoring port].
+If you have already enrolled the {agent}, consider using the Fleet UI to change the agent's HTTP monitoring endpoint
+using {fleet-guide}/agent-policy.html#advanced-agent-monitoring-settings[Advanced agent monitoring settings].
 ====
 
 . Enable monitoring of {agent} by adding the following settings to your `elastic-agent.yml` configuration file: