feat(manager): allow to add a footer below index without always overriding index

app/views/manager/application/index.html.erb

@@ -0,0 +1,46 @@
+<%#
+# Override original index template augmented with an optional "index_footer" partial.
+# Update it from the template with the original content:
+# https://github.com/thoughtbot/administrate/blob/main/app/views/administrate/application/index.html.erb
+
+# Index
+This view is the template for the index page.
+It is responsible for rendering the search bar, header and pagination.
+It renders the `_table` partial to display details about the resources.
+## Local variables:
+- `page`:
+  An instance of [Administrate::Page::Collection][1].
+  Contains helper methods to help display a table,
+  and knows which attributes should be displayed in the resource's table.
+- `resources`:
+  An instance of `ActiveRecord::Relation` containing the resources
+  that match the user's search criteria.
+  By default, these resources are passed to the table partial to be displayed.
+- `search_term`:
+  A string containing the term the user has searched for, if any.
+- `show_search_bar`:
+  A boolean that determines if the search bar should be shown.
+[1]: http://www.rubydoc.info/gems/administrate/Administrate/Page/Collection
+%>
+<%=
+  render("index_header",
+    resources: resources,
+    search_term: search_term,
+    page: page,
+    show_search_bar: show_search_bar,
+  )
+%>
+
+<section class="main-content__body main-content__body--flush">
+  <%= render(
+    "collection",
+    collection_presenter: page,
+    collection_field_name: resource_name,
+    page: page,
+    resources: resources,
+    table_title: "page-title"
+  ) %>
+  <%= render("pagination", resources: resources) %>
+</section>
+
+<%= render("index_footer") %>