Fix doc image location

Author: akru

drone_employee/doc/quick_drone_setup.md

@@ -29,7 +29,7 @@ Constructors takes several arguments, e.g. *Air traffice controller* address(pub
 
 The experimental *Air traffic controller* up for *Tamalpais state park* area.
 
-![Tamalpais area](https://raw.githubusercontent.com/DroneEmployee/drone_employee_ros/demo_march/drone_employee/doc/tamalpais_region.png)
+![Tamalpais area](https://raw.githubusercontent.com/DroneEmployee/drone_employee_ros/master/drone_employee/doc/tamalpais_region.png)
 
 **Air traffic controller:**