HDFS-6187. Update the document of hftp/hsftp in branch-2 to mention that they are deprecated.

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/Hftp.md

@@ -16,11 +16,18 @@ HFTP Guide
 ==========
 
 * [HFTP Guide](#HFTP_Guilde)
+     * [Deprecated](#Deprecated)
      * [Introduction](#Introduction)
      * [Implementation](#Implementation)
      * [Configuration Options](#Configuration_Options)
 
 
+Deprecated
+----------
+HFTP and HSFTP are deprecated in 2.x and will be unavailable in 3.0.
+They have been superseded by [WebHDFS](WebHDFS.html).
+
+
 Introduction
 ------------