message: docs: proposal window ascii
diff: @@ -87,6 +87,16 @@ impl<'a, P: ChainProvider> RewardCalculator<'a, P> {
  }
  /// Earliest proposer get 40% of tx fee as reward when tx committed
  + /// block H(19) target H(13) ProposalWindow(2, 5)
  + /// target current
  + /// / /
  + /// 10 11 12 13 14 15 16 17 18 19
  + /// \ \ \ \______/___/___/___/
  + /// \ \ \________/___/___/
  + /// \ \__________/___/
  + /// \____________/
  + ///
  +
  pub fn proposal_reward(
  &self,
  parent: &Header,
  