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

Please make sure you have the correct access rights
and the repository exists.

$ git remote -v
heroku git@heroku.com:example.git (fetch)
heroku git@heroku.com:example.git (push)

git remote add heroku git@heroku.com:example.git

$ git push heroku master

$ git remote -v