modify library list api

app/views/libraries/index.json.jbuilder

@@ -11,6 +11,11 @@ json.libraries do
     json.published_at library.display_published_at
     json.created_at library.display_created_at
 
-    json.tags library.library_tags.map(&:name)
+    # 标签
+    json.tags do
+      json.array! library.library_tags.each do |tag|
+        json.extract! tag, :id, :name
+      end
+    end
   end
 end