Mark tag-specific feeds as "tag" collection

Author: somini

lib/jekyll-feed/generator.rb

@@ -90,7 +90,7 @@ def generate_tag_feed(tags_pool, tags_path)
         path = "#{tags_path}#{tag_slug}.xml"
         next if file_exists?(path)
 
-        @site.pages << make_page(path, :tags => tag)
+        @site.pages << make_page(path, :collection => "tag", :tags => tag)
       end
     end