Do not display neoforge for 1.20.1 or show a warning

[IThundxr]

NeoForge 1.20.1 is completely unmaintained, and its developers advise users to use mcforge for 1.20.1 and earlier, it's way behind mcforge and users know don't know end up encountering crashes due to it being outdated.

It should either be removed from the meta entirely or show a very clear warning that its advised to use mcforge instead as neoforge 1.20.1 is unmaintained.