Update configs to allow for mod upgrades

[Akaitatsu]

Expected behavior Upgrading mods shouldn't generate errors for missing config settings.

• Fix current issues as described below
• Update development documentation to include log checks when upgrading mods

Actual behavior Example from forge.log when splitting logs:

[11Nov2020 14:45:14.744] [modloading-worker-14/WARN] [net.minecraftforge.common.ForgeConfigSpec/CORE]: Configuration file G:\AMPDatastore\Instances\SheepWagonRampage\Minecraft\config\mysticalworld-common.toml is not correct. Correcting
[11Nov2020 14:45:14.745] [modloading-worker-14/WARN] [net.minecraftforge.common.ForgeConfigSpec/CORE]: Incorrect key mob_spawns.Hell Sprout_spawn was corrected from null to SimpleCommentedConfig:{}

[Akaitatsu]

Most configurations applied in Mod Snacks appear to be fixed. Druidcraft is still having an issue, so we'll see what's going on there.