HBASE-27295 Correct the comment of list_deadservers method in admin.rb (#4694)

Signed-off-by: Duo Zhang <[email protected]>
Signed-off-by: Tak Lon (Stephen) Wu <[email protected]>

Author: 2005hithlj

hbase-shell/src/main/ruby/hbase/admin.rb

@@ -1610,7 +1610,7 @@ def clear_compaction_queues(server_name, queue_name = nil)
     end
 
     #----------------------------------------------------------------------------------------------
-    # clear dead region servers
+    # list dead region servers
     def list_deadservers
       @admin.listDeadServers.to_a
     end