incorrect link and deadlink in lod_tensor_en.rst (#745)

1.  Word2vec , Individual Recommendation , Sentiment Analysis in the beginner's guide 三篇文档的链接指向了中文文档，修正为英文文档
2. Fluid Model Library文档由于更改了名字，链接变为死链，进行了修正

doc/fluid/user_guides/howto/basic_concept/lod_tensor_en.rst

@@ -299,6 +299,6 @@ Summary
 
 Then, we believe that you have known about the concept LoD-Tensor. And an attempt to change x_d and y_d in code above and then to check the output may help you get a better understanding of this flexible structure.
 
-About more model applications of LoDTensor, you can refer to `Word2vec <../../../beginners_guide/basics/word2vec/index.html>`_ , `Individual Recommendation <../../../beginners_guide/basics/recommender_system/index.html>`_ , `Sentiment Analysis <../../../beginners_guide/basics/understand_sentiment/index.html>`_ in the beginner's guide. 
+About more model applications of LoDTensor, you can refer to `Word2vec <../../../beginners_guide/basics/word2vec/index_en.html>`_ , `Individual Recommendation <../../../beginners_guide/basics/recommender_system/index_en.html>`_ , `Sentiment Analysis <../../../beginners_guide/basics/understand_sentiment/index_en.html>`_ in the beginner's guide. 
 
-About more difffiult and complex examples of application, please refer to associated information about `models <../../../user_guides/models/model12_en.html>`_ .
+About more difffiult and complex examples of application, please refer to associated information about `models <../../../user_guides/models/index_en.html>`_ .