[DOCS] Revise workaround for aggregated fields in threshold rules (#2074

)

* Remove workaround from create rule docs

* Restore admonition, with revisions from Madison

docs/detections/rules-ui-create.asciidoc

@@ -164,18 +164,8 @@ For example, if `Group by` is `source.ip`, `destination.ip` and its `Threshold`
 +
 You can also leave the `Group by` field undefined. The rule then creates an alert when the number of search results is equal to or greater than the threshold value. If you set `Count` to limit the results by `process.name` >= 2, an alert will only be generated for source/destination IP pairs that appear with at least 2 unique process names across all events.
 +
-[IMPORTANT]
-==============
-Signals created by *threshold* rules are synthetic signals that do not resemble the source documents. The signal itself only contains data about the fields that were aggregated over (the `Group by` fields). Additionally, the signal contains "lookup" data for retrieving a *Timeline* of all of the source events that caused the threshold to be exceeded.
-If you wish to create an <<rule-notifications, *Action*>> based on a threshold rule, you can obtain values of the fields that were aggregated over by entering the following:
-```
-{{#context.alerts}}
-  {{#signal.threshold_result.terms}}
-    {{value}}
-  {{/signal.threshold_result.terms}}
-{{/context.alerts}}
-```
-==============
+IMPORTANT: Alerts created by threshold rules are synthetic alerts that do not resemble the source documents. The alert itself only contains data about the fields that were aggregated over (the `Group by` fields). Other fields are omitted, because they can vary across all source documents that were counted toward the threshold. Additionally, you can reference the actual count of documents that exceeded the threshold from the `kibana.alert.threshold_result.count` field.
+
 . Continue with <<preview-rules, previewing the rule>> (optional) or click *Continue* to <<rule-ui-basic-params, configure basic rule settings>>.
 
 [discrete]