Blank map issue, Google Maps API not enabled (react-native-maps#1706)

You need to enable Google maps API in the google developer console for android/ios

Author: abiduzz420

README.md

@@ -452,6 +452,7 @@ Pass an array of coordinates to focus a map region on said coordinates.
 * Make sure that you have [properly installed](docs/installation.md) react-native-maps.
 * Check in the logs if there is more informations about the issue.
 * Try setting the style of the MapView to an absolute position with top, left, right and bottom values set.
+* Make sure you have enabled Google Maps API in ![Google developer console](https://console.developers.google.com/apis/library)
 
 ```javascript
 const styles = StyleSheet.create({