[ISSUE #6085] Fix a typo

controller/src/main/java/org/apache/rocketmq/controller/impl/DLedgerController.java

@@ -78,7 +78,7 @@ public class DLedgerController implements Controller {
     private final EventSerializer eventSerializer;
     private final RoleChangeHandler roleHandler;
     private final DLedgerControllerStateMachine statemachine;
-    // Usr for checking whether the broker is alive
+    // use for checking whether the broker is alive
     private BiPredicate<String, String> brokerAlivePredicate;
     // use for elect a master
     private ElectPolicy electPolicy;