Slim down help command.

lib/jekyll/commands/help.rb

@@ -5,8 +5,8 @@ module Jekyll
 
         def init_with_program(prog)
           prog.command(:help) do |c|
-            c.syntax 'help <command>'
-            c.description 'Show the help for'
+            c.syntax 'help [subcommand]'
+            c.description 'Show the help message, optionally for a given subcommand.'
 
             c.action do |args, _|
               if args.empty?
@@ -18,12 +18,6 @@ module Jekyll
           end
         end
 
-        def usage_message(prog, cmd)
-          Jekyll.logger.error "Error:", "No command specified."
-          Jekyll.logger.warn  "Usage:", cmd.syntax
-          Jekyll.logger.info  "Valid commands:", prog.commands.keys.join(", ")
-        end
-
       end
     end
   end