add readme

README.md

@@ -167,6 +167,8 @@ python -m paddlerec.run -m ./models/rank/dnn/config.yaml -b backend.yaml
 |   召回   |                [Word2Vec](models/recall/word2vec/model.py)                |      ✓      |      x      |       ✓       |
 |   召回   |                     [SSR](models/recall/ssr/model.py)                     |      ✓      |      ✓      |       ✓       |
 |   召回   |                 [Gru4Rec](models/recall/gru4rec/model.py)                 |      ✓      |      ✓      |       ✓       |
+|   召回   |                 [Youtube_dnn](models/recall/youtube_dnn/model.py)                 |      ✓      |      ✓      |       ✓       |
+|   召回   |                 [Ncf](models/recall/ncf/model.py)                 |      ✓      |      ✓      |       ✓       |
 |   排序   |                      [Dnn](models/rank/dnn/model.py)                      |      ✓      |      x      |       ✓       |
 |   排序   |                   [DeepFM](models/rank/deepfm/model.py)                   |      ✓      |      x      |       ✓       |
 |   排序   |                  [xDeepFM](models/rank/xdeepfm/model.py)                  |      ✓      |      x      |       ✓       |