Add known issue for integration default output

Author: kilfoyle

docs/en/ingest-management/release-notes/release-notes-8.16.asciidoc

@@ -234,6 +234,19 @@ curl -XPOST -H 'Authorization: Bearer ${TOKEN}' -H 'x-elastic-product-origin:fle
 ----
 ====
 
+[discrete]
+[[known-issue-206131]]
+.
+[%collapsible]
+====
+*Details* +
+Beginning in version 8.16.0 you can specify an output per integration policy. However, setting the integration output to the default creates an invalid output name.
+
+*Impact* +
+Until this issue is resolved, as a workaround you can clone the default output before setting as the output for a specific integration policy. Refer to issue link:https://github.com/elastic/kibana/issues/206131[#206131] for details.
+
+====
+
 [discrete]
 [[new-features-8.16.0]]
 === New features