message: docs: fix the doc of task
diff: @@ -538,7 +538,7 @@ Therefore you can just treat the `TaskRuntime` object a stateless event emitter.
  // every node, parent or child will emit finish event when it finish
  });
  - runtime.on("node-error", (error, node) => {
  + runtime.on("fail", (error, node) => {
  // emit when a task node (parent or child) failed
  });
  