Updating lot that is now jury plaza in Houston, TX (#328)

An email came in to prompt this update:

> ...the city block bounded by Congress, Caroline, Franklin & San
Jacinto is no longer a parking lot, it’s the Harris County Jury Plaza.

This removes that block of parking. The stats don't change as the total
area only changes a small amount and still rounds to the percentage of
26%.

Author: davidrhunt