Replace lingering reference to EntityPreDamageEvent in docstring (version 1.21.1, possibly others)

Present in at least one class: `net.neoforged.neoforge.common.damagesource.DamageContainer#addModifier`.

Git Link:
https://github.com/neoforged/NeoForge/blob/1.21.1/src/main/java/net/neoforged/neoforge/common/damagesource/DamageContainer.java#L98