Improve work item dashboard

app/dashboards/work_item_dashboard.rb

@@ -12,6 +12,7 @@ class WorkItemDashboard < Administrate::BaseDashboard
     course: Field::BelongsTo,
     available_from: Field::DateTime,
     due_at: Field::DateTime,
+    completed_at: Field::DateTime,
     title: Field::String,
     tracked_time_entries: Field::HasMany,
     document_link: Field::String,
@@ -25,11 +26,11 @@ class WorkItemDashboard < Administrate::BaseDashboard
   # By default, it's limited to four items to reduce clutter on index pages.
   # Feel free to add, remove, or rearrange items.
   COLLECTION_ATTRIBUTES = %i[
-    id
+    title
     course
     available_from
     due_at
-    title
+    completed_at
     document_link
   ].freeze
 
@@ -45,6 +46,7 @@ class WorkItemDashboard < Administrate::BaseDashboard
     tracked_time_entries
     created_at
     updated_at
+    completed_at
   ].freeze
 
   # FORM_ATTRIBUTES
@@ -55,6 +57,7 @@ class WorkItemDashboard < Administrate::BaseDashboard
     course
     available_from
     due_at
+    completed_at
     document_link
     tracked_time_entries
   ].freeze