Reverted (docker#3393)

Author: Jim Galasyn

registry/recipes/mirror.md

@@ -100,22 +100,3 @@ to make the change persistent.
 ```
 
 Save the file and restart Docker for the change to take effect.
-
-## Use case: the China registry mirror
-
-The URL of the registry mirror for China is `registry.docker-cn.com`. You can pull 
-images from this mirror just like you do for other registries by specifying
-the full path, including the registry, in your `docker pull` command, for example:
-
-```bash
-$ docker pull registry.docker-cn.com/library/ubuntu
-```
-
-Or you can add "https://registry.docker-cn.com" to the `registry-mirrors` array
-in `/etc/docker/daemon.json` to pull from the China registry mirror by default.  
-
-```json
-{
-  "registry-mirrors": ["https://registry.docker-cn.com"]
-}
-```