Add new section to HDFS CHANGES.txt for 0.23.1. Moved two things that were recently committed post-0.23.0 to this new section.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1196905 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -1,5 +1,22 @@
 Hadoop HDFS Change Log
 
+Release 0.23.1 - UNRELEASED
+
+  INCOMPATIBLE CHANGES
+
+  NEW FEATURES
+
+  IMPROVEMENTS
+
+  OPTIMIZATIONS
+
+    HDFS-2130. Switch default checksum to CRC32C. (todd)
+
+    HDFS-2533. Remove needless synchronization on some FSDataSet methods.
+    (todd)
+
+  BUG FIXES
+
 Release 0.23.0 - 2011-11-01 
 
   INCOMPATIBLE CHANGES
@@ -789,11 +806,6 @@ Release 0.23.0 - 2011-11-01
 
     HDFS-2465. Add HDFS support for fadvise readahead and drop-behind. (todd)
 
-    HDFS-2130. Switch default checksum to CRC32C. (todd)
-
-    HDFS-2533. Remove needless synchronization on some FSDataSet methods.
-    (todd)
-
   BUG FIXES
 
     HDFS-2344. Fix the TestOfflineEditsViewer test failure in 0.23 branch.