When you go into a site, and see the green 'Deploy Now' button to the right, just below that is the 'Deployment Script' area. It's the one that does the git pull, reload php-fpm, etc.
@Xation In Forge click on a server and then on a site. The top box box as a green "Deploy now" button. The second box has a text area to edit the deployment script.
@Robstar Inside App ? No I've nothing because I'm using Envoyer.io. I add the command inside the Deployment Hooks on Envoyer. After the Purge Old Releases.