Update dedup.md - Add supported content (#4890)

It appears Monitors was missing from the list of supported content for the dedup operator. I was able to save a monitor with the dedup operator without issue.

Author: mvirga-sumo

docs/search/search-query-language/search-operators/dedup.md

@@ -15,6 +15,7 @@ The `dedup` operator is supported for the following features:
 * [Log Search](/docs/search)
 * [Dashboards](/docs/dashboards), including live mode
 * [Scheduled Searches](/docs/alerts/scheduled-searches/schedule-search.md)
+* [Monitors](/docs/alerts/monitors/)
 
 ## Syntax