message: Fixed typo in example of plugin form
  The example code for the form of a plugin with automatically bound middlewares was incorrect. The actual key the API requires is `middlewares`, not `middleware`.
diff: @@ -587,7 +587,7 @@ module.exports = function(botkit) {
  },
  // Any middlewares that should be automatically bound
  // Can include more than 1 of each kind.
  - middleware: {
  + middlewares: {
  ingest: [
  (bot, message, next) => { next(); }
  ],
  