Add ALT Linux to the list of distributions.
- vertcenter
- alpha (transparent background)
- Available in packages:
+ - ALT Linux (Sisyphus): `xst`
- Arch Linux (AUR): `xst-git`
- Fedora (COPR): `keefle/xst`
- Gentoo (personal overlay): https://framagit.org/3/ebuilds
