message: Add comment about `merkle_tree_hash_activation` in `GotRemotely` event
diff: @@ -55,6 +55,10 @@ pub(crate) enum Event<T: Item> {
  },
  /// An announcement from a different component that we have accepted and stored the given item.
  GotRemotely {
  + // TODO[RC]: `merkle_tree_hash_activation` is scattered around, because this is a piece of
  + // information obtained in the top-level code (read from the chainspec), but
  + // required across all the layers, including the very bottom ones. At some point we should
  + // consider refactoring to get rid of such "tramp data".
  merkle_tree_hash_activation: Option<EraId>,
  item: Box<T>,
  source: Source<NodeId>,
  