[DOCS] Fix missing id syntax (#121264)

* [DOCS] Fix missing id syntax

* Update docs/reference/troubleshooting/common-issues/disk-usage-exceeded.asciidoc

* fix id

Author: leemthompo

docs/reference/troubleshooting/common-issues/disk-usage-exceeded.asciidoc

@@ -127,12 +127,14 @@ its {cloud}/ec-api-console.html[Elasticsearch API Console] to later
 with this resolution flow on {ess}, kindly reach out to
 https://support.elastic.co[Elastic Support] for assistance.
 
-== Prevent watermark errors
+[discrete]
+[[fix-watermark-errors-prevent]]
+=== Prevent watermark errors
 
-To avoid watermark errors in future, , perform one of the following actions:
+To avoid watermark errors in future, perform one of the following actions:
 
 * If you're using {ess}, {ece}, or {eck}: Enable <<xpack-autoscaling,autoscaling>>.
 
 * Set up {kibana-ref}/kibana-alerts.html[stack monitoring alerts] on top of
 <<monitor-elasticsearch-cluster,{es} monitoring>> to be notified before
-the flood-stage watermark is reached.
+the flood-stage watermark is reached.