[DOCS] Adds important admonition to handling delayed data page (#97753) (#97805)

Author: szabosteve

docs/reference/ml/anomaly-detection/ml-delayed-data-detection.asciidoc

@@ -16,6 +16,12 @@ if it is set too high, analysis drifts farther away from real-time. The balance
 that is struck depends upon each use case and the environmental factors of the
 cluster.
 
+IMPORTANT: If you get an error that says
+`Datafeed missed XXXX documents due to ingest latency`, consider increasing 
+the value of `query_delay'. If it doesn't help, investigate the ingest latency and its 
+cause. You can do this by comparing event and ingest timestamps. High latency 
+is often caused by bursts of ingested documents, misconfiguration of the ingest 
+pipeline, or misalignment of system clocks.
 == Why worry about delayed data?
 
 If data are delayed randomly (and consequently are missing from analysis), the

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/messages/Messages.java

@@ -154,7 +154,7 @@ public final class Messages {
     public static final String JOB_AUDIT_DATAFEED_NO_DATA = "Datafeed has been retrieving no data for a while";
     public static final String JOB_AUDIT_DATAFEED_MISSING_DATA =
         "Datafeed has missed {0} documents due to ingest latency, latest bucket with missing data is [{1}]."
-            + " Consider increasing query_delay";
+            + " Consider increasing query_delay and investigate the cause of high latency in your ingestion process.";
     public static final String JOB_AUDIT_DATAFEED_RECOVERED = "Datafeed has recovered data extraction and analysis";
     public static final String JOB_AUDIT_DATAFEED_STARTED_FROM_TO = "Datafeed started (from: {0} to: {1}) with frequency [{2}]";
     public static final String JOB_AUDIT_DATAFEED_STARTED_REALTIME = "Datafeed started in real-time";