Add a high level diagram.

Tweak output.

doc/README

-Linux/Mac OS X
-==============
-To install doxygen: 
-$sudo apt-get install doxygen
+Mac OS X
+========
+To install doxygen and dot: 
+brew install doxygen dot
 
 doxyqml:
 https://github.com/agateau/doxyqml
@@ -10,5 +10,5 @@ $sudo pip3 install doxyqml
 Then to generate the html, run the following code while you are in the qgroundcontrol/doc directory:
 $doxygen Doxyfile
 
-The html file index.html should be in doc/html unless you chenged the output directory. 
+The html file index.html should be in doc/html. 
 

doc/qgroundcontrol.md

 QGroundControl Architecture Documentation {#mainpage}
 =========================================
 
+#### High Level Diagram
+
+<div align="center">
+<img src="../qgcmain.svg" style="width:80%; height=auto;">
+</div>
+
 * [Link Management](links.md)
 * [Vehicle Management](vehicleMgmt.md)

doc/vehicleMgmt.md

@@ -7,7 +7,7 @@ it emits MAVLinkProcotol::vehicleHeartbeatInfo signals.
 The singleton MultiVehicleManager is responsible for creating and maintaining instances of the Vehicle class. When it receives a MAVLinkProcotol::vehicleHeartbeatInfo
 signal for the first time, it creates a vehicle instance, recording the vehicle ID and the link used. 
 
-The Vehicle class holds all the functionality to handle vehicles. It receives all messages sent from the vehicle and manage all messages and commands to that vehicle.
+The Vehicle class holds all the functionality to handle vehicles. It receives all messages sent from the vehicle and manages all messages and commands to that vehicle.
 
 <div align="center">
 <img src="../vehicleMgmt.svg" style="width:80%; height=auto;">