HDFS-11978. Remove invalid '-usage' command of 'ec' and add missing commands 'addPolicies' 'listCodecs' in doc. Contributed by wenxin he.

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

@@ -444,7 +444,8 @@ Usage:
          [-getPolicy -path <path>]
          [-unsetPolicy -path <path>]
          [-listPolicies]
-         [-usage [cmd ...]]
+         [-addPolicies -policyFile <file>]
+         [-listCodecs]
          [-help [cmd ...]]
 
 | COMMAND\_OPTION | Description |
@@ -453,6 +454,8 @@ Usage:
 |-getPolicy| Get ErasureCoding policy information about a specified path|
 |-unsetPolicy| Unset an ErasureCoding policy set by a previous call to "setPolicy" on a directory |
 |-listPolicies| Lists all supported ErasureCoding policies|
+|-addPolicies| Add a list of erasure coding policies|
+|-listCodecs| Get the list of supported erasure coding codecs and coders in system|
 
 Runs the ErasureCoding CLI. See [HDFS ErasureCoding](./HDFSErasureCoding.html#Administrative_commands) for more information on this command.
 

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

@@ -156,7 +156,6 @@ Deployment
          [-listPolicies]
          [-addPolicies -policyFile <file>]
          [-listCodecs]
-         [-usage [cmd ...]]
          [-help [cmd ...]]
 
 Below are the details about each command.
@@ -187,4 +186,4 @@ Below are the details about each command.
 
  *  `[-listCodecs]`
 
-     Get the list of supported erasure coding codecs and coders in system. A coder is an implementation of a codec. A codec can have different implementations, thus different coders. The coders for a codec are listed in a fall back order.
+     Get the list of supported erasure coding codecs and coders in system. A coder is an implementation of a codec. A codec can have different implementations, thus different coders. The coders for a codec are listed in a fall back order.