Update docs for v8.16.6 release (elastic#125451)

Author: elasticsearchmachine

docs/reference/release-notes.asciidoc

@@ -6,6 +6,7 @@
 
 This section summarizes the changes in each release.
 
+* <<release-notes-8.16.6>>
 * <<release-notes-8.16.5>>
 * <<release-notes-8.16.4>>
 * <<release-notes-8.16.3>>
@@ -81,6 +82,7 @@ This section summarizes the changes in each release.
 
 --
 
+include::release-notes/8.16.6.asciidoc[]
 include::release-notes/8.16.5.asciidoc[]
 include::release-notes/8.16.4.asciidoc[]
 include::release-notes/8.16.3.asciidoc[]

docs/reference/release-notes/8.16.6.asciidoc

@@ -0,0 +1,29 @@
+[[release-notes-8.16.6]]
+== {es} version 8.16.6
+
+coming[8.16.6]
+
+Also see <<breaking-changes-8.16,Breaking changes in 8.16>>.
+
+[[bug-8.16.6]]
+[float]
+=== Bug fixes
+
+Infra/Core::
+* Prevent rare starvation bug when using scaling `EsThreadPoolExecutor` with empty core pool size. {es-pull}124732[#124732] (issue: {es-issue}124667[#124667])
+
+Machine Learning::
+* Migrate `model_version` to `model_id` when parsing persistent elser inference endpoints {es-pull}124769[#124769] (issue: {es-issue}124675[#124675])
+
+Search::
+* Do not let `ShardBulkInferenceActionFilter` unwrap / rewrap ESExceptions {es-pull}123890[#123890]
+* Revert fail-fast disconnect strategy for `_resolve/cluster` {es-pull}124241[#124241]
+
+[[upgrade-8.16.6]]
+[float]
+=== Upgrades
+
+Security::
+* Bump nimbus-jose-jwt to 10.0.2 {es-pull}124544[#124544]
+
+