Update index_en.rst

doc/fluid/user_guides/index_en.rst

@@ -26,6 +26,8 @@ Overview
     - `Recommend <../user_guides/rec_case/index_en.html>`_：introduces cases of using paddle to realize Recommend tasks
 
 	- `Models Zoo <../user_guides/models/index_en.html>`_：introduces the models zoo of Paddle
+	
+    - `Tools <../user_guides/tools/index_en.html>`_：introduces cases of using paddle tools
 
 ..  toctree::
     :hidden:
@@ -35,7 +37,7 @@ Overview
     nlp_case/index_en.rst
     rec_case/index_en.rst
 	models/index_cn.rst
-
+    tools/index_en.rst
 
 We packaged Jupyter, PaddlePaddle, and various dependency softwares into a Docker image. It frees you from installing these softwares by yourself, and you only need to just install Docker. For various Linux versions, please refer to https://www.docker.com . If you use docker on `Windows <https://www.docker.com/docker-windows>`_ or `Mac <https://www.docker.com/docker-mac>`_ , consider `allocate more Memory and CPU resources to Docker  <http://stackoverflow.com/a/39720010/724872>`_ .