Add a CHANGES.txt file for HDFS-1623 branch

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-1623@1153937 13f79535-47bb-0310-9956-ffa450edef68

hdfs/CHANGES.HDFS-1623.txt

@@ -0,0 +1,5 @@
+Changes for HDFS-1623 branch.
+
+This change list will be merged into the trunk CHANGES.txt when the HDFS-1623
+branch is merged.
+------------------------------