Explicitly note removal of System V init scripts

https://issues.jenkins.io/browse/JENKINS-71787 noted that the System V
based initalization of Amazon Linux AMI (AL1) does not support systemd
and thus cannot upgrade past Jenkins 2.416.

Amazon Linux AMI (AL1) reached end of regular support in 2020.  Extended
maintenance support ends Dec 31, 2023.

content/_data/changelogs/weekly.yml

@@ -20903,8 +20903,12 @@
         pr_title: "RPM: Remove System V initialization script"
         references:
           - url: https://github.com/jenkinsci/packaging/pull/409
-            title: RPM Remove System V initialization script
+            title: pull 409 (packaging)
+          - url: https://www.jenkins.io/blog/2022/03/25/systemd-migration/
+            title: Linux install packages migrated from System V init to system
         message: |-
+          Remove System V initialization scripts from RPM based installers.
+          The System V initialization scripts were replaced in March 2022 with systemd initialization.
           RPM users with a custom log directory no longer have a <code>logrotate(8)</code> configuration out-of-the-box.
       - type: rfe
         category: rfe