message: Fix method name in comment
diff: @@ -71,7 +71,7 @@ pub trait BlockService {
  /// blocks as they are created.
  type BlockSubscription: Stream<Item = Self::Header, Error = Error>;
  - /// The type of asynchronous futures returned by method `subscribe`.
  + /// The type of asynchronous futures returned by method `block_subscription`.
  ///
  /// The future resolves to a stream that will be used by the protocol
  /// implementation to produce a server-streamed response.
  