install nvm into oh my zsh code example

Example: how use nvm with zsh

git clone https://github.com/lukechilds/zsh-nvm ~/.oh-my-zsh/custom/plugins/zsh-nvm
// edit .zshrc file and add to plugins
plugins+=(zsh-nvm)
// After the save, close the terminal re-open and install the version of node you want
nvm install 12
// Magically works!