Update _index.md

restore the `redirectto`, add reason in comments

content/topics/_index.md

@@ -2,5 +2,8 @@
 title: "Topics"
 summary: ""
 primary_image: "topics-og-primary-image"
-expirydate: 2024-07-03
+redirectto: "https://digital.gov/resources/"
+# Using redirectto instead of alias as there are nearly 400 Hugo shortcodes
+# example {{< ref "/topics/mobile" >}}
+
 ---