update npm and node code example

Example 1: update npm

npm install -g npm@latest

Example 2: upgrade npm

npm i -g npm-upgrade

Example 3: update node js version ubuntu

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

Example 4: update npm

npm install -g npm@latest 
// for global install

Example 5: npm latest version windows

npm-windows-upgrade --npm-path "C:\nodejs"