Merge pull request #3023 from emqx/readme

Add docker installation docs to README

README-CN.md

@@ -20,7 +20,13 @@
 
 *EMQ X* 是跨平台的，支持 Linux、Unix、Mac OS 以及 Windows。这意味着 *EMQ X* 可以部署在 x86_64 架构的服务器上，也可以部署在 Raspberry Pi 这样的 ARM 设备上。
 
-获取适合你的二进制软件包，[点此下载](https://emqx.io/downloads)。
+**使用 EMQ X Docker 镜像安装**
+
+```
+docker run -d --name emqx -p 1883:1883 -p 8083:8083 -p 8883:8883 -p 8084:8084 -p 18083:18083 emqx/emqx
+```
+
+**或者 [点此下载](https://emqx.io/downloads) 适合你的二进制软件包**
 
 - [单节点安装](https://docs.emqx.io/broker/v3/cn/install.html)
 - [集群安装](https://docs.emqx.io/broker/v3/cn/cluster.html)

README.md

@@ -20,7 +20,13 @@ Starting from 3.0 release, *EMQ X* broker fully supports MQTT V5.0 protocol spec
 
 The *EMQ X* broker is cross-platform, which supports Linux, Unix, Mac OS and Windows. It means *EMQ X* can be deployed on x86_64 architecture servers and ARM devices like Raspberry Pi.
 
-Download the binary package for your platform from [here](https://emqx.io/downloads).
+**Installing via EMQ X Docker Image**
+
+```
+docker run -d --name emqx -p 1883:1883 -p 8083:8083 -p 8883:8883 -p 8084:8084 -p 18083:18083 emqx/emqx
+```
+
+**Or download the binary package for your platform from [here](https://emqx.io/downloads).**
 
 - [Single Node Install](https://docs.emqx.io/broker/v3/en/install.html)
 - [Multi Node Install](https://docs.emqx.io/broker/v3/en/cluster.html)