Action item to update API Guideline doc..

Hi All,

Here is the newest version of the API guideline doc that incorporates why WebIDL is being used and assumptions on vehicle types covered by our work (passenger, and not transportation or heavy machinery, for example).
Andy had updated it, but I don't think he sent it out.
I will also update the link in the wiki to point to the new version (v4).

Thanks,
Tina