update heroku cli code example

Example 1: heroku cli

npm i -g heroku
code to install heroku in windows

Example 2: download heroku cli mac os catalina

$ brew tap heroku/brew && brew install heroku

Example 3: how to install heroku cli

sudo apt-get install heroku

Example 4: heroku cli install

$ curl https://cli-assets.heroku.com/install.sh | sh

Example 5: heroku cli

$ sudo snap install --classic heroku