[Improvement]Add comments to ZKMasterClient.java(#5005)

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/zk/ZKMasterClient.java

@@ -77,7 +77,7 @@ public class ZKMasterClient extends AbstractZKClient {
     public void start(MasterServer masterServer) {
         InterProcessMutex mutex = null;
         try {
-            // create distributed lock with the root node path of the lock space as /dolphinscheduler/lock/failover/master
+            // create distributed lock with the root node path of the lock space as /dolphinscheduler/lock/failover/startup-masters
             String znodeLock = getMasterStartUpLockPath();
             mutex = new InterProcessMutex(getZkClient(), znodeLock);
             mutex.acquire();