Update 8.17.4 release notes to warn of http_poller issue (#17436)

(cherry picked from commit 3cde776)

Author: jsvd

docs/static/releasenotes.asciidoc

@@ -85,6 +85,11 @@ This section summarizes the changes in the following releases:
 [[logstash-8-17-4]]
 === Logstash 8.17.4 Release Notes
 
+[[known-issues-8-17-4]]
+==== Known issues
+
+** The https://github.com/logstash-plugins/logstash-input-http_poller[http_poller input] plugin will terminate during pipeline startup due to an issue with an underlying library. Please upgrade to logstash-input-http_poller 5.6.1 using {ls}'s plugin manager with `bin/logstash-plugin update logstash-input-http_poller`.
+
 [[notable-8-17-4]]
 ==== Notable issues fixed
 
@@ -3296,4 +3301,4 @@ 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