Docs: link fix

docs/howto/README.md

@@ -45,11 +45,6 @@
 - [How to train Prediction's MLP model](how_to_train_prediction_mlp_model_cn.md)
 - [How to use the navigation mode of Apollo 2.5 cn](how_to_use_apollo_2.5_navigation_mode_cn.md)
 
-
-## Preparing the environment and porting to other distros
-- [How to set up a network](how_to_set_up_a_network.md)
-- [How to prepare Centos based GPU enabled image for ROS perception module](how_to_prepare_centosbased_gpu_enabled_image_for_ROS_perception_module.md)
-
 ## Architecture
 - [How to understand Apollo's core architecture and workflow](how_to_understand_architecture_and_workflow.md)
 

docs/howto/how_to_set_up_a_network.md

-### How to Set up the Network
-
-### Helpful hints before you begin:
-
-* The IPC that is running the Apollo software must access the Internet to acquire the Real Time Kinematic (RTK) data for accurate localization. A mobile device also needs to connect to the IPC to run the Apollo software.
-* It is recommended that you configure a fixed IP instead of using DHCP on the IPC to make it easier to connect to from a mobile terminal.
-* Itis recommends that you set up your network according to the following diagram:
-
-![4G_network_setup](https://github.com/tc87/apollo/blob/master/docs/quickstart/images/4G_network_setup.png)
-
-### Setting up the network:
-
-1.   Install and configure a 4G LTE router with Wi-Fi Access Point (AP) capability and Gigabit Ethernet ports.
-
-
-2.   Connect the IPC to the LTE router using an Ethernet cable.
-
-
-3.   Configure the LTE router to access the Internet using the LTE cellular network.
-
-
-4.   Configure the AP capability of the LTE router so that the iPad Pro or another mobile device can connect to the router, and, in turn, connect to the IPC.