[docker] update install page.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

README.md

@@ -1,4 +1,4 @@
-<img src="docs/logo.png" width="350" align="right">
+<img src="https://github.com/skygragon/leetcode-cli/raw/master/docs/logo.png" width="350" align="right">
 
 # leetcode-cli
 

docs/install.md

@@ -5,49 +5,57 @@ title: Installation
 
 # Prerequisites
 
-`node.js` (`npm` included) required, please follow the installation guide:
+Install the latest LTS version of `node.js` (`npm` included):
 
 * [Install from package manager](https://nodejs.org/en/download/package-manager/)
 * [Install from directly download](https://nodejs.org/en/download/)
 
-Please install the latest LTS version on the list above.
-
-Then verify the result:
+Check before going next:
 
 	$ node -v
 	$ npm -v
 
 # Installation
 
-Choose one of the following ways to install leetcode-cli:
+There are different ways to install `leetcode-cli`:
 
 ### From npm
 
-This will install the latest stable version, but not include the latest development version.
+This will install the latest STABLE version, but not include the latest DEV version.
 
     $ npm install -g leetcode-cli
+    $ leetcode version
 
-In case Ubuntu failed due to `permission denied`, run following and try again:
+In case Ubuntu failed due to **permission denied**, try following:
 
 	$ curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash
 	$ source ~/.bashrc
 	$ nvm install --lts
 
-See more details [here](https://docs.npmjs.com/getting-started/fixing-npm-permissions).
+Find more details [here](https://docs.npmjs.com/getting-started/fixing-npm-permissions).
 
 ### From GitHub
 
-This will install the latest development version on GitHub.
+This will install the latest DEV version from GitHub repo.
 
 	$ npm install -g skygragon/leetcode-cli
+	$ leetcode version
 
-### From local source
+### From source
 
 Similar with above, while you can introduce your own changes as you wish.
 
     $ git clone http://github.com/skygragon/leetcode-cli
     $ cd leetcode-cli && ./bin/install
+    $ leetcode version
+
+### From docker
 
-Then verify the result:
+NOTE: This is just a tiny taste to let you feel that leetcode-cli is. Please use other ways above to install leetcode-cli if you like it.
 
+	$ alias leetcode='docker run -it --rm skygragon/leetcode-cli'
 	$ leetcode version
+
+To persistent user data, you can mount a folder like this:
+
+	$ alias leetcode='docker run -it --rm -v /Users/skygragon/data:/root skygragon/leetcode-cli'