improved description

Author: riyakhdl

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml

@@ -2468,11 +2468,11 @@
   </property>
 
   <property>
-    <description>Normally, we do not need to set this configuration. The class would be loaded from customized classpath
-      if it does not belongs to system-classes. For example, by default, the package org.apache.hadoop is in the
-      system-classes, if your class CustomAuxService is in the package org.apache.hadoop, it would not be loaded
-      from customized classpath. To solve this, either we could change the package for CustomAuxService, or configure
-      our own system-classes which exclude org.apache.hadoop.</description>
+    <description>Normally this configuration shouldn't be manually set. The class would be loaded from customized
+      classpath if it does not belong to system-classes. By default, the package org.apache.hadoop is part of the
+      system-classes. If for example the class CustomAuxService is in the package org.apache.hadoop, it will not be
+      loaded from the customized classpath. To solve this, either the package of CustomAuxService could be changed,
+      or a separate system-classes could be configured which excludes the package org.apache.hadoop.</description>
     <name>yarn.nodemanager.aux-services.%s.system-classes</name>
     <value></value>
   </property>