Setup instructions for CloudAnchorExample sample app

To use:
1) The sample app uses Firebase. See https://firebase.google.com/docs/ios/setup for setup instructions.
   Download the GoogleService-Info.plist file and place it next to Info.plist.
2) Modify ExampleViewController.m to use your API key (search for sessionWithAPIKey:).
3) Run pod install.
4) Open CloudAnchorExample.xcworkspace.
5) Change bundle ID, so that you can sign the app with your team.