message: Update readme.md
  fixing typo in 'Start from Scratch' code
diff: @@ -63,7 +63,7 @@ var Botkit = require('botkit');
  var controller = Botkit.slackbot(configuration);
  -controller.hears('hello','direct_mesage', function(bot, message) {
  +controller.hears('hello','direct_message', function(bot, message) {
  bot.reply(message,'Hello yourself!');
  });
  ```
  