[Security] 8.18.4 release notes (#6912) (#6939)

* [Security] 8.18.4 release notes

* Tweaks

* adds missing RN

* address feedback

* Adds another note

* and another one

* Add more RM notes

* full stop

(cherry picked from commit dfd8418)

Co-authored-by: natasha-moore-elastic <[email protected]>

Author: mergify[bot]

docs/release-notes.asciidoc

@@ -3,6 +3,7 @@
 
 This section summarizes the changes in each release.
 
+* <<release-notes-8.18.4, {elastic-sec} version 8.18.4>>
 * <<release-notes-8.18.3, {elastic-sec} version 8.18.3>>
 * <<release-notes-8.18.2, {elastic-sec} version 8.18.2>>
 * <<release-notes-8.18.1, {elastic-sec} version 8.18.1>>

docs/release-notes/8.18.asciidoc

@@ -1,6 +1,31 @@
 [[release-notes-header-8.18.0]]
 == 8.18
 
+[discrete]
+[[release-notes-8.18.4]]
+=== 8.18.4
+
+[discrete]
+[[enhancements-8.18.4]]
+==== Enhancements
+* Improves logging of fatal exceptions in {elastic-defend}.
+* Allows {elastic-defend} users to control the maximum file size for malware protection using the `advanced.malware.max_file_size_bytes` advanced policy setting.
+
+[discrete]
+[[bug-fixes-8.18.4]]
+==== Fixes
+* Fixes differences between risk scoring preview and persisted risk scores ({kibana-pull}226456[#226456]).
+* Fixes domain validation in case observables ({kibana-pull}225901[#225901]).
+* Updates a placeholder and validation message in the **Related Integrations** section of the rule upgrade flyout ({kibana-pull}225775[#225775]).
+* Excludes {ml} rules from installation and upgrade checks for users with Basic or Essentials licenses ({kibana-pull}224676[#224676]).
+* Allows using days as a time unit in rule schedules, fixing an issue where durations normalized to days were incorrectly displayed as 0 seconds ({kibana-pull}224083[#224083]).
+* Strips `originId` from connectors before rule import to ensure correct ID regeneration and prevent errors when migrating connector references on rules ({kibana-pull}223454[#223454]).
+* Refactors Timeline styling for improved consistency with design updates ({kibana-pull}222438[#222438]).
+* Fixes a bug where the **Rules**, **Alerts**, and **Fleet** pages would stall in air-gapped environments ({kibana-pull}220510[#220510]).
+* Fixes a bug where unmodified prebuilt rules installed before v8.18 didn't appear in the **Upgrade** table when the **Unmodified** filter was selected ({kibana-pull}227859[#227859]).
+* Improves UI copy for the "bulk update with conflicts" modal ({kibana-pull}227803[#227803]).
+* Fixes an issue in {elastic-defend} that may result in bugchecks (BSODs) on Windows systems with a very high volume of network connections. This issue has only been observed on Windows Server.
+
 [discrete]
 [[release-notes-8.18.3]]
 === 8.18.3