fix formula in comment
@@ -61,7 +61,7 @@ impl<C: Get<Balance>> Convert<Weight, Balance> for LinearWeightToFee<C> {
/// Update the given multiplier based on the following formula
///
-/// diff = (target_weight - previous_block_weight)
+/// diff = (previous_block_weight - target_weight)
/// v = 0.00004
/// next_weight = weight * (1 + (v . diff) + (v . diff)^2 / 2)
///
