From what I can tell Pterodactyl is a collection of software which, as @IAmGav said, is designed for game server management. That said, one of the components is a standard Nginx web server install with config added for the Pterodactyl Panel web interface.
Conceivably it would be possible to install Discourse alongside Pterodactyl in much the same way as described here:
This would be an advanced and unsupported install of Discourse, however. It would require good knowledge of Linux server administration and it would require that you have Pterodactyl installed on a system that you have root access to.