docs(readme): add links

Author: craftzdog

README.md

@@ -87,7 +87,7 @@ db.transaction(function(txn) {
 })
 ```
 
-There is a test app in the [test directory](https://github.com/craftzdog/react-native-sqlite-2/tree/master/test).
+See [an example project](/example/) for more detail.
 
 ### Using with PouchDB
 
@@ -111,6 +111,10 @@ As part of database initialization, this library will enable foreign key support
 
 See [CHANGELOG.md](./CHANGELOG.md)
 
+## Contributing
+
+See [CONTRIBUTING.md](./CONTRIBUTING.md)
+
 ## Original Cordova SQLite Bindings from Nolan Lawson
 
 https://github.com/nolanlawson/cordova-plugin-sqlite-2