Known issue for 8.15.1 related to env vars references (#16455)

docs/static/releasenotes.asciidoc

@@ -69,6 +69,15 @@ This section summarizes the changes in the following releases:
 [[logstash-8-15-1]]
 === Logstash 8.15.1 Release Notes
 
+[[known-issues-8-15-1]]
+==== Known issues
+
+* **{ls} may fail to start under some circumstances.** Single and double quotes are stripped from a pipeline configuration if the configuration includes environment or keystore variable references.
+If this situation occurs, {ls} may fail to start or some plugins may use a malformed configuration.
+Check out issue https://github.com/elastic/logstash/issues/16437[#16437] for details.
++
+Workaround: Downgrade to {ls} 8.15.0, or temporarily avoid using environment and keystore variable references.
+
 [[notable-8.15.1]]
 ==== Performance improvements and notable issues fixed
 
@@ -2475,4 +2484,4 @@ 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