HBASE-12601 Explain how to grant/revoke permission to a group/namespace in grant/revoke command usage (Ashish Singhi)

hbase-shell/src/main/ruby/shell/commands/grant.rb

@@ -27,11 +27,14 @@ Syntax : grant <user> <permissions> [<@namespace> [<table> [<column family> [<co
 permissions is either zero or more letters from the set "RWXCA".
 READ('R'), WRITE('W'), EXEC('X'), CREATE('C'), ADMIN('A')
 
-Note: A namespace must always precede with '@' character.
+Note: Groups and users are granted access in the same way, but groups are prefixed with an '@' 
+      character. In the same way, tables and namespaces are specified, but namespaces are 
+      prefixed with an '@' character.
 
 For example:
 
     hbase> grant 'bobsmith', 'RWXCA'
+    hbase> grant '@admins', 'RWXCA'
     hbase> grant 'bobsmith', 'RWXCA', '@ns1'
     hbase> grant 'bobsmith', 'RW', 't1', 'f1', 'col1'
     hbase> grant 'bobsmith', 'RW', 'ns1:t1', 'f1', 'col1'

hbase-shell/src/main/ruby/shell/commands/revoke.rb

@@ -22,10 +22,17 @@ module Shell
       def help
         return <<-EOF
 Revoke a user's access rights.
-Syntax : revoke <user> [<table> [<column family> [<column qualifier>]]
+Syntax : revoke <user> [<@namespace> [<table> [<column family> [<column qualifier>]]]]
+
+Note: Groups and users access are revoked in the same way, but groups are prefixed with an '@' 
+      character. In the same way, tables and namespaces are specified, but namespaces are 
+      prefixed with an '@' character.
+
 For example:
 
     hbase> revoke 'bobsmith'
+    hbase> revoke '@admins'
+    hbase> revoke 'bobsmith', '@ns1'
     hbase> revoke 'bobsmith', 't1', 'f1', 'col1'
     hbase> revoke 'bobsmith', 'ns1:t1', 'f1', 'col1'
 EOF

hbase-shell/src/main/ruby/shell/commands/user_permission.rb

@@ -23,9 +23,13 @@ module Shell
         return <<-EOF
 Show all permissions for the particular user.
 Syntax : user_permission <table>
+
+Note: A namespace must always precede with '@' character.
+
 For example:
 
     hbase> user_permission
+    hbase> user_permission '@ns1'
     hbase> user_permission 'table1'
     hbase> user_permission 'namespace1:table1'
     hbase> user_permission '.*'