YARN-9203. Fix typos in yarn-default.xml.

This closes #437

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

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

@@ -539,8 +539,8 @@
 
       This property allows users to set ACLs of their choice instead of using
       the default mechanism. For fencing to work, the ACLs should be
-      carefully set differently on each ResourceManger such that all the
-      ResourceManagers have shared admin access and the Active ResourceManger
+      carefully set differently on each ResourceManager such that all the
+      ResourceManagers have shared admin access and the Active ResourceManager
       takes over (exclusively) the create-delete access.
     </description>
     <name>yarn.resourcemanager.zk-state-store.root-node.acl</name>