update README

Basic configiuration information added.

Author: Shhzdmrz

README.md

@@ -1 +1,17 @@
 # ReactNativeBackgroundTimer
+
+## An example react native application to test react-native-background-timer
+
+### React Native Config
+
+- react = 16.5.0
+- react-native = 0.57.0
+- react-native-background-timer = 2.1.1
+
+### Android config
+
+- buildToolsVersion = 27.0.3
+- minSdkVersion = 16
+- compileSdkVersion = 27
+- targetSdkVersion = 26
+- supportLibVersion = 27.1.1