Update install content AND Add raspberry-pi

install/ubuntu.md

@@ -134,6 +134,41 @@ $ sudo groupadd docker
 $ sudo usermod -aG docker $USER
 ```
 
+### 测试 Docker 是否安装正确
+
+```bash
+$ docker run hello-world
+
+Unable to find image 'hello-world:latest' locally
+latest: Pulling from library/hello-world
+ca4f61b1923c: Pull complete
+Digest: sha256:be0cd392e45be79ffeffa6b05338b98ebb16c87b255f48e297ec7f98e123905c
+Status: Downloaded newer image for hello-world:latest
+
+Hello from Docker!
+This message shows that your installation appears to be working correctly.
+
+To generate this message, Docker took the following steps:
+ 1. The Docker client contacted the Docker daemon.
+ 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
+    (amd64)
+ 3. The Docker daemon created a new container from that image which runs the
+    executable that produces the output you are currently reading.
+ 4. The Docker daemon streamed that output to the Docker client, which sent it
+    to your terminal.
+
+To try something more ambitious, you can run an Ubuntu container with:
+ $ docker run -it ubuntu bash
+
+Share images, automate workflows, and more with a free Docker ID:
+ https://cloud.docker.com/
+
+For more examples and ideas, visit:
+ https://docs.docker.com/engine/userguide/
+```
+
+若能正常输出以上信息，则说明安装成功。
+
 ### 镜像加速
 
 鉴于国内网络问题，后续拉取 Docker 镜像十分缓慢，强烈建议安装 Docker 之后配置 [国内镜像加速](mirror.md)。
@@ -141,4 +176,3 @@ $ sudo usermod -aG docker $USER
 ### 参考文档
 
 * [Docker 官方 Ubuntu 安装文档](https://docs.docker.com/engine/installation/linux/docker-ce/ubuntu/)
-* [阿里云 Docker CE 安装镜像帮助](https://yq.aliyun.com/articles/110806)