commit the additional doc change for HDFS-6717

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615801 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10928. Incorrect usage on . Contributed by Josh Elser.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615808 13f79535-47bb-0310-9956-ffa450edef68