README Driven Development

Inspiration: [RDD](http://tom.preston-werner.com/2010/08/23/readme-driven-development.html)

* [x] tease some example usage
* [x] installation and enabling tab completion
* [x] demonstrate command usage
  * [x] `work` usage
  * [x] `ls` usage
* [x] explain alerts/notifications when timer is done
* [x] `TODO` section to eat our own dog food