Add Fleet & Agent 8.11.3 Release Notes (#748)

* Add Fleet & Agent 8.11.3 Release Notes

* Add notes

* Add security update for Elastic Agent

(cherry picked from commit 15b3a78)

docs/en/ingest-management/release-notes/release-notes-8.11.asciidoc

@@ -14,6 +14,7 @@
 
 This section summarizes the changes in each release.
 
+* <<release-notes-8.11.3>>
 * <<release-notes-8.11.2>>
 * <<release-notes-8.11.1>>
 * <<release-notes-8.11.0>>
@@ -23,6 +24,29 @@ Also see:
 * {kibana-ref}/release-notes.html[{kib} release notes]
 * {beats-ref}/release-notes.html[{beats} release notes]
 
+// begin 8.11.3 relnotes
+
+[[release-notes-8.11.3]]
+== {fleet} and {agent} 8.11.3
+
+Review important information about {fleet-server} and {agent} for the 8.11.3 release.
+
+[discrete]
+[[security-updates-8.11.3]]
+=== Security updates
+
+{agent}::
+The 8.11.3 patch release contains a fix for a potential security vulnerability. Please see our link:https://discuss.elastic.co/c/announcements/security-announcements/31[security advisory for more details].
+
+[discrete]
+[[bug-fixes-8.11.3]]
+=== Bug fixes
+
+{fleet}::
+* Fix a 500 error in the {fleet} API when a request for the product versions endpoint throws `ECONNREFUSED`. ({kibana-pull}172850[#172850])
+* Fix {agent} policy timeout to accept only integers. ({kibana-pull}172222[#172222])
+
+// end 8.11.3 relnotes
 
 // begin 8.11.2 relnotes