Server Tuning: fixed table, added units, added pure gametype info

I fixed the `grenade_curvature` entry, added some units to the table so that you actually know what you are changing and what it does. The units are not complete as I don't know how to describe every variable. I also added some information about the gametype as I see many people not knowing that they need to change the gametype to `mod` to use tuning.