docs(readme): added current version shield

Author: Christian Elies

README.md

@@ -2,6 +2,7 @@
 
 [![Swift 5.1](https://img.shields.io/badge/swift5.1-compatible-green.svg?longCache=true&style=flat-square)](https://developer.apple.com/swift)
 [![Platform](https://img.shields.io/badge/platform-iOS%20%7C%20macOS%20%7C%20tvOS-lightgrey.svg?longCache=true&style=flat-square)](https://www.apple.com)
+[![Current Version](https://img.shields.io/github/v/tag/crelies/RemoteImage?longCache=true&style=flat-square)](https://github.com/crelies/RemoteImage)
 [![License](https://img.shields.io/badge/license-MIT-lightgrey.svg?longCache=true&style=flat-square)](https://en.wikipedia.org/wiki/MIT_License)
 
 This Swift package provides a wrapper view around the existing **SwiftUI** `Image view` which adds support for showing and caching remote images.