Update use-third-party-application.md as per...
Update use-third-party-application.md as per https://github.com/Chocobozzz/PeerTube/issues/754#issuecomment-544129319
Update use-third-party-application.md as per https://github.com/Chocobozzz/PeerTube/issues/754#issuecomment-544129319