Update changelog for older versions

Author: moxarth-rathod

packages/o365/changelog.yml

@@ -4,6 +4,11 @@
     - description: Populate `message` field from the O365 Audit Log fields instead of `Subject` field in ComplianceDLPExchange events to better reflect Alert Titles.
       type: enhancement
       link: https://github.com/elastic/integrations/pull/14587
+- version: "2.18.6"
+  changes:
+    - description: Stricter enforcement of maximum age limits.
+      type: bugfix
+      link: https://github.com/elastic/integrations/pull/14567
 - version: "2.18.5"
   changes:
     - description: Ensure numeric Yammer IDs are not rendered with E-notation.