update comments

fe/fe-core/src/main/java/org/apache/doris/qe/Coordinator.java

@@ -2888,7 +2888,8 @@ public void unsetFields() {
  // Has to use synchronized to ensure there are not concurrent update threads. Or the done
  // state maybe update wrong and will lose data. see https://github.com/apache/doris/pull/29802/files.
  public synchronized boolean updatePipelineStatus(TReportExecStatusParams params) {
- // The fragment or instance is not finished, still need update progress
+ // The fragment or instance is not finished, still need handle the report to update the load progress.
+ // Otherwise the load progress (ScannedRows/LoadBytes) won't be updated before any instance is done.
  if (!params.done) {
  return true;
  }