Add demo GIF to Read Me

Author: dhavallogistic

README.md

@@ -4,6 +4,10 @@
 * No need to generate Google API key for geocoding functionality in react-native anymore.
 * This lib returns the Address/Lat-Lang WITHOUT using GOOGLE API key
 
+## Demo
+
+![This demo.](/react-native-geocoding-reversegeocoding.gif "This is a sample.")
+
 ## Installation
 
 ```sh