HDFS-9021. Use a yellow elephant rather than a blue one in diagram.

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

@@ -886,6 +886,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-9002. Move o.a.h.hdfs.net/*Peer classes to hdfs-client.
     (Mingliang Liu via wheat9)
 
+    HDFS-9021. Use a yellow elephant rather than a blue one in diagram. (wang)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than