Release notes for 8.11.1 (#15572)

docs/static/releasenotes.asciidoc

@@ -3,6 +3,7 @@
 
 This section summarizes the changes in the following releases:
 
+* <<logstash-8-11-1,Logstash 8.11.1>>
 * <<logstash-8-11-0,Logstash 8.11.0>>
 * <<logstash-8-10-4,Logstash 8.10.4>>
 * <<logstash-8-10-3,Logstash 8.10.3>>
@@ -48,6 +49,11 @@ This section summarizes the changes in the following releases:
 * <<logstash-8-0-0-alpha1,Logstash 8.0.0-alpha1>>
 
 
+[[logstash-8-11-1]]
+=== Logstash 8.11.1 Release Notes
+
+* Downgrade jackson to avoid serialization issues when log.format is set to "json" https://github.com/elastic/logstash/pull/15549[#15549]
+
 [[logstash-8-11-0]]
 === Logstash 8.11.0 Release Notes
 
@@ -1867,4 +1873,4 @@ We have added another flag to the Benchmark CLI to allow passing a data file wit
 This feature allows users to run the Benchmark CLI in a custom test case with a custom config and a custom dataset. https://github.com/elastic/logstash/pull/12437[#12437]
 
 ==== Plugin releases
-Plugins align with release 7.14.0
+Plugins align with release 7.14.0