Move pipelines to the root dir (PaddlePaddle#3012)

* Move pipelines to the root dir

* Add missing files

applications/experimental/pipelines/examples/question-answering/Install_windows.md → pipelines/examples/question-answering/Install_windows.md

@@ -7,6 +7,7 @@
 ### 1.1 运行环境和安装说明
 
 a. 依赖安装：
+首先需要安装PaddlePaddle，PaddlePaddle的安装请参考文档[官方安装文档](https://www.paddlepaddle.org.cn/install/quick?docurl=/documentation/docs/zh/install/pip/linux-pip.html)，然后安装下面的依赖：
 ```bash
 pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple
 # 1) 安装 pipelines package

applications/experimental/pipelines/examples/question-answering/README.md → pipelines/examples/question-answering/README.md

@@ -45,6 +45,7 @@ b. 硬件环境：
 - Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
 
 c. 依赖安装：
+首先需要安装PaddlePaddle，PaddlePaddle的安装请参考文档[官方安装文档](https://www.paddlepaddle.org.cn/install/quick?docurl=/documentation/docs/zh/install/pip/linux-pip.html)，然后安装下面的依赖：
 ```bash
 pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple
 # 1) 安装 pipelines package

applications/experimental/pipelines/examples/semantic-search/Install_windows.md → pipelines/examples/semantic-search/Install_windows.md

@@ -6,6 +6,7 @@
 ### 1.1 运行环境和安装说明
 
 a. 依赖安装：
+首先需要安装PaddlePaddle，PaddlePaddle的安装请参考文档[官方安装文档](https://www.paddlepaddle.org.cn/install/quick?docurl=/documentation/docs/zh/install/pip/linux-pip.html)，然后安装下面的依赖：
 ```bash
 pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple
 # 1) 安装 pipelines package

applications/experimental/pipelines/examples/semantic-search/README.md → pipelines/examples/semantic-search/README.md

@@ -50,6 +50,7 @@ b. 硬件环境：
 - Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
 
 c. 依赖安装：
+首先需要安装PaddlePaddle，PaddlePaddle的安装请参考文档[官方安装文档](https://www.paddlepaddle.org.cn/install/quick?docurl=/documentation/docs/zh/install/pip/linux-pip.html)，然后安装下面的依赖：
 ```bash
 pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple
 # 1) 安装 pipelines package

applications/experimental/pipelines/requirements.txt → pipelines/requirements.txt

@@ -1,4 +1,3 @@
-paddlepaddle-gpu
 paddlenlp
 paddleocr
 requests

applications/experimental/pipelines/setup.py → pipelines/setup.py

@@ -19,12 +19,8 @@
 
 long_description = "PIPELINES: An End to End Natural Language Proceessing Development Kit Based on ERNIE"
 
-if platform.system().lower() == "darwin":  # macos
-    with open("requirements-cpu.txt") as fin:
-        REQUIRED_PACKAGES = fin.read()
-else:
-    with open("requirements.txt") as fin:
-        REQUIRED_PACKAGES = fin.read()
+with open("requirements.txt") as fin:
+    REQUIRED_PACKAGES = fin.read()
 
 setuptools.setup(name="pipelines",
                  version=pipelines.__version__,