[WAF] Add release note (#22776)

Author: pedrosousa

src/content/release-notes/waf-general.yaml

@@ -7,6 +7,10 @@ topLevelLink: "/waf/change-log/"
 productArea: Application security
 productAreaLink: /fundamentals/reference/changelog/security/
 entries:
+  - publish_date: "2025-05-28"
+    title: Updated attack score model
+    description: |-
+      We have deployed an updated attack score model focused on enhancing the detection of multiple false positives (FPs). As a result of this improvement, some changes in observed attack scores are expected.
   - publish_date: "2025-03-07"
     title: Updated leaked credentials database
     description: |-