add dselect_k fix space_doc

Author: wangzhen38

README_EN.md

@@ -155,7 +155,7 @@ python -u tools/static_trainer.py -m models/rank/dnn/config.yaml #  Training wit
   |      Multi-Task       |                  [MMOE](models/multitask/mmoe/)<br>([doc](https://paddlerec.readthedocs.io/en/latest/models/multitask/mmoe.html))                   |  [Python CPU/GPU](https://aistudio.baidu.com/aistudio/projectdetail/3238934)  |         ✓         |     ✓     |      >=2.1.0     | [KDD 2018][Modeling Task Relationships in Multi-task Learning with Multi-gate Mixture-of-Experts](https://dl.acm.org/doi/abs/10.1145/3219819.3220007)                                                       |
   |      Multi-Task       |           [ShareBottom](models/multitask/share_bottom/)<br>([doc](https://paddlerec.readthedocs.io/en/latest/models/multitask/share_bottom.html))           |  [Python CPU/GPU](https://aistudio.baidu.com/aistudio/projectdetail/3238943)  |         ✓         |     ✓     |  >=2.1.0 | [1998][Multitask learning](http://reports-archive.adm.cs.cmu.edu/anon/1997/CMU-CS-97-203.pdf)                                                                                                               |
   |      Multi-Task       |           [Maml](models/multitask/maml/)<br>([doc](https://paddlerec.readthedocs.io/en/latest/models/multitask/maml.html))           |  [Python CPU/GPU](https://aistudio.baidu.com/aistudio/projectdetail/3238412)  |    x      |     x     | >=2.1.0 | [PMLR 2017][Model-agnostic meta-learning for fast adaptation of deep networks](https://arxiv.org/pdf/1703.03400.pdf)                                                                                                               |
-  |  Multi-Task  |           [DSelect_K](models/multitask/dselect_k/)([doc](https://paddlerec.readthedocs.io/en/latest/models/multitask/dselect_k.html))           |  -  |      x      |     x     | >=2.1.0 | [NeurIPS 2021][DSelect-k: Differentiable Selection in the Mixture of Experts with Applications to Multi-Task Learning](https://arxiv.org/pdf/2106.03760v3.pdf)                                                                                                               |
+  |  Multi-Task  |           [DSelect_K](models/multitask/dselect_k/)<br>([doc](https://paddlerec.readthedocs.io/en/latest/models/multitask/dselect_k.html))           |  -  |      x      |     x     | >=2.1.0 | [NeurIPS 2021][DSelect-k: Differentiable Selection in the Mixture of Experts with Applications to Multi-Task Learning](https://arxiv.org/pdf/2106.03760v3.pdf)                                                                                                               |
   |        Re-Rank        |                [Listwise](https://github.com/PaddlePaddle/PaddleRec/tree/release/1.8.5/models/rerank/listwise/)                |  -  |         ✓         |     x     |  [1.8.5](https://github.com/PaddlePaddle/PaddleRec/tree/release/1.8.5) | [2019][Sequential Evaluation and Generation Framework for Combinatorial Recommender System](https://arxiv.org/pdf/1902.00245.pdf)                                                                           |
 
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