Update README.md

quad/src/virt_quad/README.md

-The Virtual Quadcopter
-----
+# The Virtual Quadcopter
 Look at how modular our quad is ... it can even run in a Unix environment!
 
 But really, this isn't just some token project, this is pretty useful for
@@ -7,7 +6,13 @@ debugging routine things in the quad_app without having to fire up the
 plethoria of things required for flight in Coover 3050. In fact, you don't 
 even have to be in Coover 3050...
 
-# Using the Virtual Quad
+## Building
+To build just the virtual quad, in this folder:
+```
+make
+```
+
+## Using the Virtual Quad
 The virt-quad has help output. Get started with:
 ```
 ./virt-quad