Add dirt modifier to other ground-based crops

[patrick1bauer]

If dirt as a crop growth modifier is supposed to incentivize people to grow their crops on the ground instead of making sky farms, why is wheat the only crop affected by this?
The dirt modifier should be added to all other soil crops (carrots, potatoes, beets)

[wingzero54]

I think it's just a leftover entry as an example soil bonus for the config, I don't think the dirt bonus is meant as a way to nerf sky farms like CivRealms