Add find_by_discid method.

lib/musicbrainz/models/release.rb

@@ -10,7 +10,7 @@ module MusicBrainz
     field :asin, String
     field :barcode, String
     field :quality, String
-    
+
     def tracks
       @tracks ||= client.load(:release, { id: id, inc: [:recordings, :media], limit: 100 }, {
         binding: :release_tracks,
@@ -26,6 +26,13 @@ module MusicBrainz
           create_model: :release
         })
       end
+
+      def find_by_discid(id)
+        client.load(:discid, { id: id, inc: [:media, :release_groups] }, {
+          binding: :release_group_releases,
+          create_models: :release
+        })
+      end
     end
   end
 end