update_en_structure (#429)

* update_en_structure

* remove doc/fluid/api/.DS_Store

doc/fluid/api/index_cn.rst

 =============
-API 说明文档
+API Reference
 =============
 
 ..  toctree::
     :maxdepth: 1
 
     api_guides/index.rst
-
     fluid.rst
     average.rst
     backward.rst

doc/fluid/api/index_en.rst

@@ -5,8 +5,6 @@ API Reference
 ..  toctree::
     :maxdepth: 1
 
-    api_guides/index.rst
-
     fluid.rst
     average.rst
     backward.rst

doc/fluid/beginners_guide/index.rst

@@ -13,7 +13,7 @@ PaddlePaddle (PArallel Distributed Deep LEarning)是一个易用、高效、灵
 
 当您第一次来到PaddlePaddle，请您首先阅读以下文档，了解安装方法：
 
-    - `安装说明 <../beginners_guide/install/Start.html>`_：我们支持在Ubunt/CentOS/Windows/MacOS环境上的安装
+    - `安装说明 <../beginners_guide/install/Start.html>`_：我们支持在Ubuntu/CentOS/Windows/MacOS环境上的安装
 
 如果您初次接触深度学习，在学习PaddlePaddle之前建议您先阅读以下资料：
 
@@ -36,7 +36,7 @@ PaddlePaddle (PArallel Distributed Deep LEarning)是一个易用、高效、灵
 
 ..  toctree::
     :maxdepth: 2
-    
+
     install/Start.rst
     quick_start/index.rst
     basics/index.rst

doc/fluid/book/index_en.rst

+Book
+======
+
+..  toctree::
+  :maxdepth: 1
+
+  ../beginners_guide/basics/index.rst
+  ../beginners_guide/quick_start/index.rst

doc/fluid/dev/index_en.rst

@@ -11,6 +11,5 @@ Development
   new_op_kernel.md
   use_eigen_en.md
   name_convention.md
-  support_new_device.md
   releasing_process_en.md
   op_markdown_format.md

doc/fluid/index_en.rst

@@ -9,5 +9,7 @@
   design/index_en.rst
   howto/index_en.rst
   dev/index_en.rst
-  faq/index_en.rst
   api/index_en.rst
+  book/index_en.rst
+  user_guides/models/index_en.rst
+  advanced_usage/deploy/index_mobile.rst

doc/fluid/user_guides/models/index_en.rst

+############################################################################
+`Models <https://github.com/PaddlePaddle/models/tree/develop/fluid>`_
+############################################################################
+
+PaddlePaddle provides a rich set of computational units to enable users to adopt a modular approach to solving various learning problems. In this repo, we demonstrate how to use PaddlePaddle to solve common machine learning tasks, providing several different neural network model that anyone can easily learn and use.
+
+
+- `fluid models <https://github.com/PaddlePaddle/models/tree/develop/fluid>`_ : use PaddlePaddle's Fluid APIs. We especially recommend users to use Fluid models.
+
+- `legacy models <https://github.com/PaddlePaddle/models/tree/develop/legacy>`_ : use PaddlePaddle's v2 APIs.