* Update attribute
Update `device tracker` attribute to reflect changes in iOS app with release of 2.0/2019
* Change known_devices.yaml example explanation
iOS App 2.0/2019 no long users `known_devices.yaml` so change explanation of example to something that does.
Reword
* Update notification example
Update example automation to reflect changes in in ios app (now used cross-platform domain `mobile_app`)
* Update to reference companion apps
The simplest solution to get battery level is with the companion apps so this should be made clear.
* Add android
We have an android app now 🎉
