Update README with Drag and Drop technique for installation.
Update README with Drag and Drop technique for installation.

See this thread for the reason why: https://github.com/joshuapinter/react-native-unified-contacts/issues/15

joshuapinter/react-native-unified-contacts,joshuapinter/react-native-unified-contacts,joshuapinter/react-native-unified-contacts,joshuapinter/react-native-unified-contacts