Update CHANGES.txt for HDFS-8238.

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

@@ -297,6 +297,9 @@ Release 2.8.0 - UNRELEASED
 
     HDFS-7164. Feature documentation for HDFS-6581. (Arpit Agarwal)
 
+    HDFS-8238. Move ClientProtocol to the hdfs-client.
+    (Takanobu Asanuma via wheat9)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than