update readme.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

README.md

@@ -68,6 +68,7 @@ It's like Laravel Homestead but for Docker instead of Vagrant.
 		- [Enable Global Composer Build Install](#Enable-Global-Composer-Build-Install)
 		- [Install Prestissimo](#Install-Prestissimo)
 		- [Install Node + NVM](#Install-Node)
+		- [Install Node + YARN](#Install-Yarn)
 		- [Debugging](#debugging)
 		- [Upgrading LaraDock](#upgrading-laradock)
 - [Help & Questions](#Help)
@@ -1125,6 +1126,30 @@ It should be like this:
 
 3 - Re-build the container `docker-compose build workspace`
 
+<br>
+<a name="Install-Yarn"></a>
+### Install Node + YARN
+
+Yarn is a new package manager for JavaScript. It is so faster than npm, which you can find [here](http://yarnpkg.com/en/compare).To install NodeJS and [Yarn](https://yarnpkg.com/) in the Workspace container:
+
+1 - Open the `docker-compose.yml` file
+
+2 - Search for the `INSTALL_NODE` and `INSTALL_YARN` argument under the Workspace Container and set it to `true`
+
+It should be like this:
+
+```yml
+    workspace:
+        build:
+            context: ./workspace
+            args:
+                - INSTALL_NODE=true
+                - INSTALL_YARN=true
+    ...
+```
+
+3 - Re-build the container `docker-compose build workspace`
+
 <br>
 <a name="Install-Aerospike-Extension"></a>
 ### Install Aerospike extension