update heroku 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: heroku cli

$ sudo snap install --classic heroku

Example 4: how to update heroku

heroku update
#(OR)
sudo apt update && sudo apt install heroku
# to update heroku