Merge pull request #30603 from tophj-ibm/fix-systemd-dropin-link

Update systemd drop-in link

contrib/init/sysvinit-debian/docker.default

@@ -4,7 +4,7 @@
 # THIS FILE DOES NOT APPLY TO SYSTEMD
 #
 #   Please see the documentation for "systemd drop-ins":
-#   https://docs.docker.com/engine/articles/systemd/
+#   https://docs.docker.com/engine/admin/systemd/
 #
 
 # Customize location of Docker binary (especially for development testing).