Update CHANGES.txt to move HDFS-4772 to 2.1.0 section

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1495542 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -8,8 +8,6 @@ Release 2.3.0 - UNRELEASED
 
   IMPROVEMENTS
 
-    HDFS-4772. Add number of children in HdfsFileStatus. (brandonli)
-
   OPTIMIZATIONS
 
   BUG FIXES
@@ -186,6 +184,8 @@ Release 2.1.0-beta - UNRELEASED
 
     HDFS-4883. complete() should verify fileId. (Tao Luo via shv)
 
+    HDFS-4772. Add number of children in HdfsFileStatus. (brandonli)
+
   OPTIMIZATIONS
 
   BUG FIXES