Update cover visibility settings in default archetype

archetypes/default.md

@@ -5,6 +5,9 @@ date: '{{ .Date }}'
 draft: true
 ShowToc: true
 cover:
+  hidden: false # hide everywhere but not in structured data
+  hiddenInList: false # hide on list pages and home
+  hiddenInSingle: true # hide on single page
   image: "images/<image.jpg>"
   alt: "<alt text>"
   caption: "<text>"