change node version code example

Example 1: upgrade node version

nvm install v12.16.2

Example 2: change node version

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

Example 3: change node version

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

Example 4: how to change node version

nvm use --delete-prefix $NODE_VERSION

example:
nvm use --delete-prefix v8.9.4