HDFS-8523. Remove usage information on unsupported operation 'fsck -showprogress' from branch-2 (Contributed by J.Andreina)

Merged CHANGES.txt from branch-2.7

(cherry picked from commit 0ed9c2d8fec93b5dac9c305eda272ad8dfd869a9)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md

(cherry picked from commit dd98cfd328dddb01a1220786d28a80195021611b)

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md

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

@@ -942,6 +942,9 @@ Release 2.7.1 - UNRELEASED
     HDFS-8270. create() always retried with hardcoded timeout when file already
     exists with open lease (J.Andreina via vinayakumarb)
 
+    HDFS-8523. Remove usage information on unsupported operation
+    "fsck -showprogress" from branch-2 (J.Andreina via vinayakumarb)
+
 Release 2.7.0 - 2015-04-20
 
   INCOMPATIBLE CHANGES