update code on heroku code example

Example 1: deploy to heroku

$ git add .
$ git commit -m "Added a Procfile."
$ heroku login
Enter your Heroku credentials.
...
$ heroku create <app-name>
Creating arcane-lowlands-8408... done, stack is cedar
// now create procfile
//
//node app.js
// 
$ git push heroku master
-----> Node.js app detected
...
-----> Launching... done
       http://arcane-lowlands-8408.herokuapp.com deployed to Heroku

Example 2: push heroku

$ git push heroku master

Example 3: how to update heroku

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