How to create a site on heroku from Linux?

Question

Heroku

Following the instructions from this article :
♦Install snap to work with heroku
sudo apt-get install snapd
♦Install heroku
sudo snap install --classic heroku
♦Logged in to heroku
snap heroku login
♦Create a website
heroku apps: create mysite
♦Set up ssh to work remotely with github.com After that, I created a new ssh key on github, where I placed the contents of the id_rsa.pub file ♦Copied the prohrammer-site folder from github.com to my home directory
ssh-keygen -t rsa -C "[email protected]"

git clone [email protected]:<мой логин на гитхабе>/programmer-site

♦Initialized git in programmer-site folder

cd programmer-site
git init

Next, I try to launch the site on heroku I get an
git push heroku master
error

fatal:'heroku' does not appear to be a git repository
fatal: Could not read from remote repository