Stay Calm

Adds back calm4.ogg from the early days of Minecraft. Notch removed it because he said it was "too spooky" so now it does not exist in vanilla.
Music added:
Minecraft Music - Calm 4 (calm4.ogg) - YouTube
Craft it like this:
p g b
l d c
b cb p
b = Black Concrete
cb = Cobblestone
p = Pink Concrete
d = Diamond
l = Oak Log
c = Crafting Table
g = Grass Block

Mod is for Forge 1.16.5
Disc does not spawn in loot tables
Credit for calm4 goes to Markus Persson/Notch