Heroku: "No app.json located in the repo URL provided."

[erickwinz30]

Trying to create a sample app using Heroku. But it return in the heroku dashboard "No app.json located in the repo URL provided."

[noe-sautel]

@erickwinz30 Use this link: https://heroku.com/deploy?template=https://github.com/fbsamples/graph-api-webhooks-samples
No '/' at the end of the URL