New process to add your own Google Maps API key:
1. [Get a Maps API key](https://developers.google.com/maps/documentation/android-sdk/get-api-key)
1. Create a file in the `ApiDemos/kotlin/app` directory called `secure.properties` (this file should *NOT* be under version control to protect your API key)
1. Add a single line to `ApiDemos/kotlin/app/secure.properties` that looks like `MAPS_API_KEY=YOUR_API_KEY`, where `YOUR_API_KEY` is the API key you obtained in the first step
1. Build and run
* Update ApiDemos/java to latest Maps SDK for Android
* Update ApiDemos/kotlin to latest Maps SDK for Android
* Update tutorials/CurrentPlaceDetailsOnMap to new Places SDK for Android
* Update tutorials/MapWithMarker to latest Maps SDK for Android
* Update tutorials/Polygons to latest Maps SDK for Android
* Update tutorials/StyledMap to latest Maps SDK for Android
* Update README with better instructions for API key