Improvement suggestions for Geospatial primer

Hi, I noticed a couple of things which - for a newb like me - were missing in this otherwise very helpful primer:

  1. There is no explicit mention that there is actually a switch (Spacial Index), which is hidden amongst many others which you can ignore for the time being, and which you explicitly have to set when you create a new database to load the DC Landmarks into Stardog.

  2. The queries as listed will not work, and will give no indication why, unless you also include this default prefix:

prefix :