Add release notes for 8.9.2 (#7891)

Author: flobernd

docs/release-notes/release-notes-8.9.2.asciidoc

@@ -0,0 +1,14 @@
+[[release-notes-8.9.2]]
+== Release notes v8.9.2
+
+[discrete]
+=== Bug fixes
+
+ - https://github.com/elastic/elasticsearch-net/pull/7875[#7875] Fix `aggregations` property not being generated for `MultisearchBody` (issue https://github.com/elastic/elasticsearch-net/issues/7873[#7873])
+ - https://github.com/elastic/elasticsearch-net/pull/7875[#7875] Remove invalid properties from `SlowlogTresholds` (issue https://github.com/elastic/elasticsearch-net/issues/7865[#7865])
+ - https://github.com/elastic/elasticsearch-net/pull/7883[#7883] Remove leading `/` character from API urls (issue: https://github.com/elastic/elasticsearch-net/issues/7878[#7878])
+
+[discrete]
+=== Features & Enhancements
+
+- https://github.com/elastic/elasticsearch-net/pull/7869[#7869] Add support for `SimpleQueryStringQuery.flags property (issue: https://github.com/elastic/elasticsearch-net/issues/7863[#7863])

docs/release-notes/release-notes.asciidoc

@@ -6,6 +6,7 @@
 [discrete]
 == Version 8.9
 
+* <<release-notes-8.9.2,Release notes v8.9.2>>
 * <<release-notes-8.9.1,Release notes v8.9.1>>
 * <<release-notes-8.9.0,Release notes v8.9.0>>
 
@@ -33,6 +34,7 @@
 * <<release-notes-8.0.0,Release notes v8.0.0>>
 
 include::breaking-change-policy.asciidoc[]
+include::release-notes-8.9.2.asciidoc[]
 include::release-notes-8.9.1.asciidoc[]
 include::release-notes-8.9.0.asciidoc[]
 include::release-notes-8.1.3.asciidoc[]