Add CHANGES.txt for HADOOP-11021.

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -479,6 +479,9 @@ Release 2.6.0 - UNRELEASED
     HADOOP-10994. KeyProviderCryptoExtension should use CryptoCodec for 
     generation/decryption of keys. (tucu)
 
+    HADOOP-11021. Configurable replication factor in the hadoop archive
+    command. (Zhe Zhang via wang)
+
   OPTIMIZATIONS
 
     HADOOP-10838. Byte array native checksumming. (James Thomas via todd)