change versions of node code example

Example 1: change node version

Usage:
nvm install <version>       Download and install a <version>
nvm use <version>           Modify PATH to use <version>
nvm ls                      List versions (installed versions are blue)

Example 2: change node version

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.34.0/install.sh | bash