* Add support for Discord PTB and update the documentation accordingly
* Add curl as a fallback when wget is not installed
* Fix installation directory being /opt/discord-stable regardless of version
* Remove suffix from the Stable version (now simply discord/Discord)
* Exit with exit code 1 on error
* Miscellaneous minor edits and fixes
Unlike [gitkraken](https://github.com/RPM-Outpost/gitkraken), the Mageia support isn't included for now, because the Mageia repositories doesn't provide libcxx, which is required by Discord. Maybe I'll find a solution later...