add google maps v2 info to readme
add google maps v2 info to readme

RyanTech/AirMapView,lockerfish/AirMapView,BraveAction/AirMapView,bleege/AirMapView,acq/AirMapView,MAubreyK/AirMapView,acq/AirMapView,airbnb/AirMapView,airbnb/AirMapView,MAubreyK/AirMapView,bleege/AirMapView,ashcoding/AirMapView,lockerfish/AirMapView,bleege/AirMapView,lockerfish/AirMapView,ashcoding/AirMapView,RyanTech/AirMapView,RyanTech/AirMapView,airbnb/AirMapView,MAubreyK/AirMapView,BraveAction/AirMapView,BraveAction/AirMapView,acq/AirMapView