fix typo

README.md

@@ -35,7 +35,7 @@ echo "Current node.js version is $(curl -fsSL https://nodejs.org/dist/index.tab
 ```bash
 # To install a specific version rather than defaulting to latest
 # latest version at time of writing are v4.4.1 and v5.9.1
-echo "v5.9.1" > /tmp/NODE_VER
+echo "v7.9.0" > /tmp/NODEJS_VER
 ```
 
 ## Notes