fixed an error in docson.js

Made a small change in docson.js that should fix rendering of the page. If everybody agrees, let's merge into master.

![screen shot 2014-04-08 at 16 59 42](https://cloud.githubusercontent.com/assets/123201/2645061/786bf6a2-bf2e-11e3-8481-892bc3d09dcd.png)