setup yarn and npm code example

Example 1: ubuntu install yarn

sudo apt install --no-install-recommends yarn

Example 2: install yarn

curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list