[FIX-7287] change description of 'master.exec.threads' (#7588)

* [2.0.2] #7287 change description of 'master.exec.threads'

* [2.0.2] #7287 change description of 'master.exec.threads'

dolphinscheduler-server/src/main/resources/master.properties

@@ -18,12 +18,9 @@
 # master listen port
 #master.listen.port=5678
 
-# master execute thread number to limit process instances in parallel
+# Number of process instances executed in parallel
 #master.exec.threads=100
 
-# master execute task number in parallel per process instance
-#master.exec.task.num=20
-
 # master dispatch task number per batch
 #master.dispatch.task.num=3