More performance-related args for WP_Query section

See #30 - I am not loving the current styling, though. The subsections run together, and trying to use another list within that subsection messes up the visual hierarchy.

![screen shot 2014-12-18 at 4 22 20 pm](https://cloud.githubusercontent.com/assets/906334/5496153/592c97e4-86d2-11e4-9aff-8bb27223af97.png)