making faq link absolute

this appears to be necessary since this file is not just used in site but also is automatically linked whenever someone is creating a new issue  and that link goes to the github.com page, where a relative link doesn't work.  

![screen shot 2014-12-08 at 6 30 38 pm](https://cloud.githubusercontent.com/assets/633088/5349606/6ccd3a1e-7f08-11e4-9e75-d48cf4df5eff.png)