admin: Decap articles collection -> nested (depth 2) with meta.path for folder-per-article layout

app/src/web/admin/config.yml

@@ -29,7 +29,11 @@ collections:
     folder: subjects
     create: true
     slug: "{{slug}}"
-    path: "{{slug}}/{{slug}}"
+    # nested layout: subjects/<subject>/<slug>/<slug>.md
+    nested:
+      depth: 2
+    meta:
+      path: { widget: string, label: Path, index_file: _index, editable_folder: false, searchable: false }
     sortable_fields: [date, title]
     fields:
       - { name: title, label: Title, widget: string }
@@ -38,7 +42,7 @@ collections:
       - { name: kicker, label: Kicker (section tag), widget: string, required: false }
       - { name: template, label: Template, widget: string, default: article }
       - { name: subject, label: Subject, widget: relation, collection: subjects, value_field: slug, search_fields: [name], display_fields: [name] }
-      - { name: image, label: 'Cover image (upload first at /admin/media; then use: {{media:filename}})', widget: string, required: false }
+      - { name: image, label: 'Cover image (drop in this article\'s folder, then use: {{media:slug/file}})', widget: string, required: false }
       - { name: excerpt, label: Excerpt / deck, widget: text, required: false }
       - { name: tags, label: Tags, widget: list, allow_add: true, required: false }
       - { name: featured, label: Featured on front page, widget: boolean, default: false }