Fix script documentation. Thanks, Stefan!

git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk@393116 13f79535-47bb-0310-9956-ffa450edef68

bin/slaves.sh

@@ -4,7 +4,8 @@
 #
 # Environment Variables
 #
-#   HADOOP_SLAVES    File naming remote hosts.  Default is ~/.slaves
+#   HADOOP_SLAVES    File naming remote hosts.
+#     Default is ${HADOOP_CONF_DIR}/slaves.
 #   HADOOP_CONF_DIR  Alternate conf dir. Default is ${HADOOP_HOME}/conf.
 #   HADOOP_SLAVE_SLEEP Seconds to sleep between spawning remote commands.
 ##