Fix nginx ML tutorial heading (#3964)

(cherry picked from commit df4407c)

docs/en/observability/monitor-nginx-ml.asciidoc

@@ -1,6 +1,6 @@
 [discrete]
 [[monitor-nginx-ml]]
-== Part 5: Find anomalies in your nginx access logs
+== Step 5: Find anomalies in your nginx access logs
 
 Use the {integrations-docs}/nginx[nginx Elastic integration] machine learning (ML) module to help find unusual activity in your nginx access logs.
 Monitoring anomalies in your access logs helps you detect:
@@ -67,4 +67,4 @@ With the nginx ML jobs detecting anomalies, you can set rules to generate alerts
 For example, you could set up a rule on the `low_request_rate_nginx` job to alert when low request rates hit a specific severity threshold.
 When you get alerted, you can make sure your server isn't experiencing issues.
 
-Refer to {ml-docs}/ml-configuring-alerts.html[Generating alerts for anomaly detection jobs] for more on setting these rules and generating alerts.
+Refer to {ml-docs}/ml-configuring-alerts.html[Generating alerts for anomaly detection jobs] for more on setting these rules and generating alerts.