message: remove events api presence caveat from slack docs
diff: @@ -913,9 +913,6 @@ The [Events API](https://api.slack.com/events-api) is a streamlined way to build
  During development, a tool such as [localtunnel.me](http://localtunnel.me) is useful for temporarily exposing a compatible webhook url to Slack while running Botkit privately.
  -Note: Currently [presence](https://api.slack.com/docs/presence) is not supported by Slack Events API, so bot users will appear offline, but will still function normally.
  -Developers may want to create an RTM connection in order to make the bot appear online - see note below.
  -
  ### To get started with the Events API:
  1. Create a [Slack App](https://api.slack.com/apps/new)
  