New launchers

[Madis0]

As one member wanted to contribute #28 already, thought I could write down a list of things that need to be created, eventually. Feel free to contribute to any of those but they will likely stay as drafts for some time as I will not merge until I consider the launcher itself to be ready.

Each launcher needs:

• Install instructions
• Update instructions
• Mod adding instructions
• Mod disabling instructions
• Main repo readme table addition
• Descriptions' number increase
• Maybe some other references I've forgotten about

Main issue: Fabulously-Optimized/fabulously-optimized#297

• Prism Launcher (downloads from Modrinth) - worked on in Prism Launcher instructions #28
• ATLauncher (downloads from Modrinth)
• Vanilla installer (Installer for Minecraft Launcher fabulously-optimized#110)
• Modrinth Launcher (Modrinth modpack fabulously-optimized#63)
• Pojav launcher??? (Pojav Launcher instructions #56)

[Madis0]

As with the original issue, tracking this as a joint issue is unnecessary.