message: Fix missing link in `Tracker::broadcast` docs
diff: @@ -131,6 +131,8 @@ where
  ///
  /// This method publishes the given event to all the subscription streams
  /// currently open.
  + ///
  + /// [`Recipe::stream`]: trait.Recipe.html#method.stream
  pub fn broadcast(&mut self, event: Event) {
  self.subscriptions
  .values_mut()
  