[TF2] Update the Halloween Spell attribute text to include full moons in it's description.

[FrozenDragon0]

The current Halloween spell attribute text mentions that the spell is only active during event A.K.A Scream Fortress, problem here is that this has no mention of Full Moons as spells were updated during 2013 to be activated during a Full Moon.

I think this text should be updated so it mentions both Full Moons along side the current Event.

Updated text: