Update installation.rst

LINE 218
"GPU" was replaced by "CPU"
LINE 196
add "(GPU version and CPU version just choose one)"

Author: Hao Luo

docs/user/installation.rst

@@ -193,8 +193,8 @@ You can easily install Tensorlayer using pip in CMD：
 .. code-block:: bash
 
   pip install tensorflow        #CPU version
-  pip install tensorflow-gpu    #GPU version
-  pip install tensorlayer       #Install tensorlayer
+  pip install tensorflow-gpu    #GPU version (GPU version and CPU version just choose one)
+  pip install tensorlayer       #Install tensorlayer
 
 Test
 --------
@@ -215,7 +215,7 @@ If there is no error and the following output is displayed, the GPU version is s
   successfully opened CUDA library nvcuda.dll locally
   successfully opened CUDA library curand64_80.dll locally
 
-If there is no error, the GPU version is successfully installed.
+If there is no error, the CPU version is successfully installed.