Add docker compilation images

install.md

 # Install Milvus from Source Code
 
-## Software requirements
+- [Build from source](https://github.com/jielinxu/milvus/edit/0.6.0/install.md#build-from-source)
+- [Compile Milvus on Docker](https://github.com/jielinxu/milvus/edit/0.6.0/install.md#compile-milvus-on-docker)
+
+## Build from source
+
+### Requirements
 
 - Ubuntu 18.04 or higher
 
@@ -8,21 +13,21 @@
   
 - CMake 3.12 or higher
 
-##### For GPU version, you will also need:
+##### For GPU-enabled version, you will also need:
 
 - CUDA 10.0 or higher
 - NVIDIA driver 418 or higher
 
-## Compilation
+### Compilation
 
-### Step 1 Install dependencies
+#### Step 1 Install dependencies
 
 ```shell
 $ cd [Milvus root path]/core
 $ ./ubuntu_build_deps.sh
 ```
 
-### Step 2 Build
+#### Step 2 Build
 
 ```shell
 $ cd [Milvus root path]/core
@@ -31,7 +36,7 @@ or
 $ ./build.sh -t Release
 ```
 
-By default, it will build CPU version. To build GPU version, add `-g` option
+By default, it will build CPU-only version. To build GPU version, add `-g` option
 ```shell
 $ ./build.sh -g
 ```
@@ -43,7 +48,7 @@ $./build.sh -h
 
 When the build is completed, all the stuff that you need in order to run Milvus will be installed under `[Milvus root path]/core/milvus`.
 
-## Launch Milvus server
+### Launch Milvus server
 
 ```shell
 $ cd [Milvus root path]/core/milvus
@@ -68,6 +73,75 @@ To stop Milvus server, run:
 $ ./stop_server.sh
 ```
 
+## Compile Milvus on Docker
+
+With this dockerfile, you should be able to compile CPU-only or GPU-enabled Milvus on any Linux platform that run Docker. To build a GPU-enabled Milvus, you neeed to install [NVIDIA Docker](https://github.com/NVIDIA/nvidia-docker/) first.
+
+### Step 1 Pull Milvus Docker images
+
+Pull CPU-only image:
+
+```shell
+$ Docker pull milvusdb/milvus-cpu-build-env:v0.6.0-ubuntu18.04
+```
+
+Pull GPU-enabled image:
+
+```shell
+$ Docker pull milvusdb/milvus-gpu-build-env:v0.6.0-ubuntu18.04
+```
+### Step 2 Start the Docker container
+
+Start a CPU-only container:
+
+```shell
+$ Docker run -it -p 19530:19530 -d milvusdb/milvus-cpu-build-env:v0.6.0-ubuntu18.04
+```
+
+Start a GPU container:
+
+```shell
+$ Docker run — runtime=nvidia -it -p 19530:19530 -d milvusdb/milvus-gpu-build-env:v0.6.0-ubuntu18.04
+```
+To enter the container:
+
+```shell
+$ Docker exec -it [container_id] bash
+```
+### Step 3 Download Milvus source code and compile it in the container
+
+Download Milvus source code:
+
+```shell
+$ cd /home
+$ wget https://github.com/milvus-io/milvus/archive/0.6.0.zip
+```
+
+Unzip the source package:
+
+```shell
+$ Apt-get update
+$ Apt-get install unzip
+$ unzip ./0.6.0.zip
+```
+
+The source code is extracted into a folder called `milvus-0.6.0`. 
+
+If you are using a CPU-only image, compile it like this:
+```shell
+$ ./build.sh -t Release
+```
+
+For GPU-enabled image, you need to add a `-g` parameter:
+```shell
+$ ./build.sh -g -t Release
+```
+
+Then start Milvus server：
+```shell
+$ ./start_server.sh
+```
+
 ## Troubleshooting
 1. If you encounter the following error when compiling: 
 `protocol https not supported or disabled in libcurl`.