Added documentation

src/main/kotlin/net/axay/kspigot/extensions/events/PrepareItemCraftEventExtensions.kt

@@ -4,7 +4,16 @@ import org.bukkit.Material
 import org.bukkit.event.inventory.PrepareItemCraftEvent
 import org.bukkit.inventory.ItemStack
 
+/**
+ * Checks if the event is "cancelled"
+ * by returning if the material of
+ * the result is equal to [Material.AIR].
+ */
 val PrepareItemCraftEvent.isCancelled: Boolean
         get() = this.inventory.result?.type == Material.AIR
 
+/**
+ * "Cancels" this event by
+ * setting the result to [Material.AIR].
+ */
 fun PrepareItemCraftEvent.cancel() { this.inventory.result = ItemStack(Material.AIR) }