Warning for install package.

ISSUE=4603239


git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1446 1ad973e4-5ce8-4261-8a94-b56d1f490c56

Author: yuyang18

doc/build/index.rst

@@ -23,6 +23,9 @@ If you want to hack and contribute PaddlePaddle source code, following guides ca
 Build Docker Images
 -------------------
 
+Note: The intallation packages are still in pre-release 
+state and your experience of installation may not be smooth.
+
 If you want to pack docker image, the following guide can help you\:
 
 ..  toctree::

doc_cn/build_and_install/install/index.rst

@@ -4,6 +4,12 @@
 PaddlePaddle提供数个预编译的二进制来进行安装。他们包括Docker镜像，ubuntu的deb安装包等
 。欢迎贡献更多的安装包。我们更推荐使用Docker镜像来部署PaddlePaddle环境。
 
+Note: The intallation packages are still in pre-release
+state and your experience of installation may not be smooth.
+
+注意!目前PaddlePaddle的安装包还处在pre-release的状态，
+使用起来或许会不是很顺畅。
+
 ..	toctree::
 	docker_install.rst
 	ubuntu_install.rst