Adding Node.js info to the 'Requirements' section of the README.MD (eclipse-che#2699)

Signed-off-by: Ilya Buziuk <ibuziuk@redhat.com>

Author: ibuziuk

dashboard/README.md

@@ -5,8 +5,13 @@ Che Dashboard
 ==============
 
 #Requirements
+- Node.js `v4.x.x` (`v5.x.x` / `v6.x.x` are currently not supported)
+- npm
+- Bower
+- gulp
+
+Installation instructions for Node.js and npm can be found on the following [link](https://docs.npmjs.com/getting-started/installing-node). Bower and gulp are CLI utilities which are installed via npm:
 
-This  version is using bower and gulp as tools.
 ```sh
 $ npm install --global bower gulp
 ```