Add badge for node.js version requirement

Minggang Wang · Minggang Wang · commit cb7111375863 · 2018-01-26T11:26:38.000+08:00
diff --git a/README.md b/README.md
@@ -1,4 +1,4 @@
-# rclnodejs - ROS Client Library for JavaScript language[![Coverage Status](https://coveralls.io/repos/github/RobotWebTools/rclnodejs/badge.svg?branch=develop)](https://coveralls.io/github/RobotWebTools/rclnodejs?branch=develop)[![npm](https://img.shields.io/npm/dt/rclnodejs.svg)](https://www.npmjs.com/package/rclnodejs)[![GitHub license](https://img.shields.io/github/license/RobotWebTools/rclnodejs.svg)](https://github.com/RobotWebTools/rclnodejs/blob/develop/LICENSE)
+# rclnodejs - ROS Client Library for JavaScript language[![Coverage Status](https://coveralls.io/repos/github/RobotWebTools/rclnodejs/badge.svg?branch=develop)](https://coveralls.io/github/RobotWebTools/rclnodejs?branch=develop)[![npm](https://img.shields.io/npm/dt/rclnodejs.svg)](https://www.npmjs.com/package/rclnodejs)[![GitHub license](https://img.shields.io/github/license/RobotWebTools/rclnodejs.svg)](https://github.com/RobotWebTools/rclnodejs/blob/develop/LICENSE)[![node](https://img.shields.io/node/v/rclnodejs.svg)](https://nodejs.org/en/download/releases/)
 
 Branch | Linux Build | macOS Build | Windows Build |
 ------------ |  :-------------: | :-------------: | :-------------: |

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`@@ -1,4 +1,4 @@`
`1`		`-# rclnodejs - ROS Client Library for JavaScript language[![Coverage Status](https://coveralls.io/repos/github/RobotWebTools/rclnodejs/badge.svg?branch=develop)](https://coveralls.io/github/RobotWebTools/rclnodejs?branch=develop)[![npm](https://img.shields.io/npm/dt/rclnodejs.svg)](https://www.npmjs.com/package/rclnodejs)[![GitHub license](https://img.shields.io/github/license/RobotWebTools/rclnodejs.svg)](https://github.com/RobotWebTools/rclnodejs/blob/develop/LICENSE)`
	`1`	+# rclnodejs - ROS Client Library for JavaScript language[![Coverage Status](https://coveralls.io/repos/github/RobotWebTools/rclnodejs/badge.svg?branch=develop)](https://coveralls.io/github/RobotWebTools/rclnodejs?branch=develop)[![npm](https://img.shields.io/npm/dt/rclnodejs.svg)](https://www.npmjs.com/package/rclnodejs)[![GitHub license](https://img.shields.io/github/license/RobotWebTools/rclnodejs.svg)](https://github.com/RobotWebTools/rclnodejs/blob/develop/LICENSE)[![node](https://img.shields.io/node/v/rclnodejs.svg)](https://nodejs.org/en/download/releases/)
`2`	`2`
`3`	`3`	`Branch \| Linux Build \| macOS Build \| Windows Build \|`
`4`	`4`	`------------ \| :-------------: \| :-------------: \| :-------------: \|`