Show examples of the acceptable units.

Test plan:
gifs:
* https://s3.amazonaws.com/uploads.hipchat.com/6574/29028/rbjOWj2NLhWxWib/units.gif
* https://s3.amazonaws.com/uploads.hipchat.com/6574/29028/o6niUvrwe7S2eJb/week.gif

Auditors: alex