Update caveat for flex tier logs (#32396)

Flex tier logs not supported for log monitors

Author: adriantong-dd

content/en/monitors/types/log.md

@@ -40,7 +40,7 @@ To create a log monitor in Datadog, use the main navigation: [**Monitors > New M
 
 As you define the search query, the graph above the search fields updates.
 
-1. Construct a search query using the same logic as a [Log Explorer search][4].
+1. Construct a search query using the same logic as a [Log Explorer search][4]. Note that [Flex Tier logs][10], which can be shown in Log Explorer, are not supported for monitors. Only Standard Tier logs are supported.
 2. Choose to monitor over a log count, [facet][5], an attribute, or [measure][6]:
     * **Monitor over a log count**: Use the search bar (optional) and do **not** select an attribute or measure. Datadog evaluates the number of logs over a selected time frame, then compares it to the threshold conditions.
     * **Monitor over a facet or an attribute**: If a an attribute is selected, the monitor alerts over the `Unique value count` of the attribute. For example, if you have an attribute such as `user.email`, the unique value count is the number of unique user emails. Any attribute can be used in a monitor, but only facets are shown in the autocompletion.
@@ -127,3 +127,4 @@ Include a sample of 10 logs in the alert notification:
 [7]: /monitors/configuration/#advanced-alert-conditions
 [8]: /monitors/notify/
 [9]: /monitors/notify/variables/?tab=is_alert#matching-attributetag-variables
+[10]: /logs/log_configuration/flex_logs/